2019届一轮复习北师大版必二Unit5Rhythm单元学案(11页word解析版)

2019届一轮复习北师大版必二Unit5Rhythm单元学案(11页word解析版)

‎2019届一轮复习北师大版必二Unit 5Rhythm单元学案 ‎ ‎[语言基础扎根练]‎ Ⅰ.单词拼写/用所给词的适当形式填空 ‎1．He has a unique (独特的) talent. Other people cannot compare with him in this field.‎ ‎2．I'm looking for something a little more out of the ordinary (普通的)．‎ ‎3．They consider that vase to be a treasure (财宝), but in my opinion, it is just a common bottle.‎ ‎4．He represented (宣称) himself as a philosopher, who studied abroad many years ago.‎ ‎5．We gather some of the most beautiful and extraordinary (非凡的) scenery of France.‎ ‎6．The audience (观众) were amused by his amusing performance on the stage.‎ ‎7．John is not his real name, but it's one he uses to disguise his identity (身份)．‎ ‎8．I suppose that it will take a little while to develop new talent (人才)．‎ ‎9．She used to be terribly shy, but her staying abroad a year has completely transformed (改变) her.‎ ‎10．The DNA test shows that the father and the son have different types (类型) of blood.‎ ‎11．I think China will become more and more powerful (power) in the future.‎ ‎12．A thousand words will not leave so deep an impression (impress) as one deed.‎ ‎13．It is their responsibility (responsible) to ensure that the rules are enforced.‎ ‎14．I've seen her performances (perform) on television, but never in the flesh. ‎ ‎15．The sudden appearance (appear) of a policeman caused the thief to run away.‎ Ⅱ.单句改错 ‎ ‎1．He has got used to live in the big city now.live→living ‎2．The knife is used to sharpening the pencils._sharpening→sharpen ‎3．This table is too close to the door; it gets on the way. on→in ‎4．When Joe was about to start school, all signs pointed to success. Yet things turned out to be quite disappointed.disappointed→disappointing ‎5．If you want to do so, you must ask permission first.ask后加for ‎6．Several new books will have been come out by the end of next month.去掉been ‎7．Word came our national table tennis team had won all the four gold medals in the Olympic Games.came后加that ‎8．The artist recently arrived in Paris from Bulgaria by the way of Vienna.去掉the Ⅲ.补全句子 ‎ ‎1．他戒烟已经十年了。‎ It is/has been ten years since_he_smoked.‎ ‎2．他经常食言，我再也不能相信他了。‎ He has_broken_his_word_ so many times that I cannot trust him any more.‎ ‎3．我们的部门经理直接对销售副总裁负责。‎ Our department manager is_directly_responsible_to the vicepresident of sales.‎ ‎4．我们在所有的准备做好之后才开始工作。‎ We won't start the work until_all_the_preparations_have_been_made.‎ ‎5．早就到了我们采取有效措施保护环境的时候了。‎ It is high time that we took/should_take_effective_measures to protect the environment.‎ ‎6．这是你第二次假装要解雇我了。 ‎ This is the second time you have_pretended_to_dismiss_me.‎ ‎[阅读理解提速练]‎ A When The New Republic magazine predicted who would win the 2016 Nobel Prize in Literature on Oct. 6th, it said: “Not Bob Dylan. That's for sure.” However, the award came as a surprise to many. On Oct. 13th, the famous US musician was named the Nobel laureate (获奖者) by the Swedish Academy. He has created new poetic expressions within the great American song tradition, according to the organization.‎ Although Dylan, 75, is not really thought to be a literary (文学的) writer, he has given the world a lot of creative works over 50 years, especially when it comes to his folk songs.‎ In his 1985 album Biograph, Dylan wrote about the appeal of folk music to him. Rock songs weren't serious enough or didn't reflect life in a realistic way, according to Dylan. But folk was a more serious type of thing. The songs are filled with more sadness, more joy and much deeper feelings.‎ Dylan's music and lyrics spoke to many people during the 1960s. His lyrics were often about great political issues, such as the Civil Rights Movement. The 1960s was a time of change when the young were making sure that their voices were heard. The idea is most famously expressed in Dylan's The Times They Are aChangin' (1964), which warns the world, “You'd better start swimming or you'll sink like a stone, for the times they are achangin'！”‎ There were complaints that a literary prize had been given to a singer, but ancient Greek poets Homer and Sappho wrote poetic works that were meant to be listened to, that were meant to be performed, often with instruments, and it's the same way with Dylan, the Swedish Academy's permanent secretary Sara Danius told CNN.‎ It could even be said that giving the important prize to Dylan has brought back an old literary tradition. The millions whose lives Dylan's words and music have changed will surely welcome the award.‎ ‎1．Why did people feel surprised when Dylan got the Nobel Prize?‎ A．Because he was not excellent.‎ B．Because people didn't think he was a literary writer.‎ C．Because he was only interested in singing folk songs.‎ D．Because people didn't believe in him.‎ 解析：选B　细节理解题。根据第二段“Although Dylan, 75, is not really thought to be a literary (文学的) writer, he has given the world a lot of creative works over 50 years, especially when it comes to his folk songs”可知，人们认为Dylan不是文学作家，因此认为他不大可能得奖。‎ ‎2．What can we learn from the text?‎ A．Folk music reflects a real life.‎ B．Songwriters shouldn't get the prize.‎ C．People like rock music more.‎ D．Dylan is a very serious person.‎ 解析：选A　推理判断题。根据第三段和第四段的内容可推知，仿民歌歌曲与摇滚乐形成对比，反映了真实的生活。‎ ‎3．From Dylan's writing, we know he cares more about ________.‎ A．music　　　　　　　 B．his voice C．politics D．change 解析：选C　细节理解题。根据第四段第二句“His lyrics were often about great political issues, such as the Civil Rights Movement”可知，Dylan的作品大多关乎政治事件，因此，Dylan很关心政治。‎ ‎4．According to Sara Danius, ________.‎ A．Dylan is worth the prize B．Sappho should get the prize C．the Academy is worth the prize D．Homer should win the prize 解析：选A　推理判断题。根据文章倒数第二段的整体内容可推知，Sara Danius认为Dylan获得诺贝尔奖是实至名归。‎ B A recent Stanford study found that America's students are shockingly bad at telling fact from fiction in this digital age. It's apparent that something has to change in the nation's classrooms. That something, according to Professor Sam Wineburg, one of those Stanford researchers, is “practice.”‎ ‎“How do they become prepared to make the choices about what to believe, what to forward, what to post to their friends，” Wineburg asked on NPR's All Things Considered, “when teachers give no practice to them？”‎ Patricia Hunt, an experienced teacher at Wakefield High School in Arlington, Va., is doing something she has never done before: helping to pilot a new, digital course called the checkology virtual classroom. It comes from the nonprofit The News Literacy Project.‎ Hunt's students, most of them seniors, work in threes or fours. They're presented with a series of stories that are rapidly and broadly spread via the Internet. Some are false information. Some are ads. And some are pure fact.‎ ‎“We don't know which is which at this point，” laughs student Kahder Smith. “We actually have to sit down, take our time, and actually read them. And probably Google some stuff to see if it's real or not.”‎ A post claims that more than a dozen people died after receiving the flu vaccine (疫苗) in Italy and that the CDC (Centers for Disease Control) is now telling people not to get a flu shot.‎ ‎“I mean, I've heard many unconfirmed reports that the flu shot's bad for you，” student Autumn Cooper says. But instinct (直觉) tells her the story's wrong. “It just doesn't look like a reliable source. It looks like this is off Facebook and someone shared it.” Cooper labels the story “fiction”. And she's right.‎ Instead of teaching students the fundamentals of factchecking, many schools simply ignore the problem, blocking social media sites on school computers.‎ ‎“It's like teaching students to drive in the parking lot and then sending them out on the highway and saying ‘Good luck！’” says Audrey Church, president of the American Association of School Librarians.‎ 语篇解读：本文是议论文。美国的一些学校开设了教学生如何鉴别网络消息真假的课程，很多专家学者表示赞同。‎ ‎5．What does the underlined word “they” in Paragraph 2 refer to?‎ A．Stanford researchers.　　　 B．Media people.‎ C．Students. D．Teachers.‎ 解析：选C　代词指代题。根据第一段中的“America's students are shockingly bad at telling fact from fiction in this digital age”可知，在电子时代，美国的学生缺乏辨别真假消息的能力，由此可推测，这里是问“这些学生”怎样才能做好准备选择相信、传递、发布哪些消息呢？另外，根据第二段末的“when teachers give no practice to them”也可推测，这里的they指的是学生。‎ ‎6．How does Hunt run the digital course?‎ A．By inviting experts to give students lectures.‎ B．By asking students to go on the Internet together.‎ C．By taking students to a news organization regularly.‎ D．By letting students identify factual information in groups.‎ 解析：选D　细节理解题。根据第四、五段内容可知，Hunt让她的学生三四人一组鉴别真假消息。‎ ‎7．According to Church, what should schools do?‎ A．Help students improve driving skills.‎ B．Teach students how to spot false news.‎ C．Allow students to drive on the highway.‎ D．Ask students to avoid using social media.‎ 解析：选B　推理判断题。根据最后两段内容可知，Church认为学校屏蔽社交媒体的做法就像是在停车场教会学生们开车后让他们直接上高速，这样做无疑风险很大。由此可推测他反对学校屏蔽社交媒体的做法，而是希望学校能够教孩子们如何识别假新闻。‎ ‎8．What does the text mainly discuss?‎ A．The findings of a recent Stanford study.‎ B．An educational issue in the digital age.‎ C．The influence of a widely spread post.‎ D．An experienced high school teacher.‎ 解析：选B　主旨大意题。通读全文可知，本文讨论了在电子时代，老师如何帮助学生们学会鉴别网络消息的真假，这是一个教育问题。‎ C ‎(2018·河南洛阳高三第一次统考)‎ Lying alongside mountains of smelly garbage under the South American sun，Cateura is a long way from the conservatories of Prague or Vienna.Yet the township，which grew out of Paraguay's largest dump(垃圾场)，is gaining a reputation as a hothouse for musical talentand for its youth orchestra (管弦乐队)that plays instruments made from garbage.“The world sends us garbage.We send back music，”says Favio Chavez，leader of the “Recycled Orchestra”，during a recent visit by the group to Los Angeles.Orchestra members，poor children from Cateura，play violins fashioned from oven trays and guitars made from dessert dishes.The orchestra provides the youngsters an outlet and an escape，a chance to go beyond the mess of their slum(贫民窟)through the music of Mozart，and even Sinatra.“In the beginning，it was difficult to play，”says the 10yearold violinist Celeste Fleitas.“But Favio helped me learn over time.From Favio，I have learned to be more responsible and value the things I have.”‎ ‎ The destination for more than 1,500 tons of waste each day，the community has no safe drinking water and little access to electricity or sanitation(卫生设施)．Illiteracy is severe，and the children of the township often fall into d rugs，violence and crimes. ‎ Favio Chavez，a musical talent，came to Cateura as an environmental technician in 2006 and started a youth music school.He knew shopbought instruments were beyond the means of villagers whose sheds are worth less than a violin，so he approached a carpenter to make some out of waste from the dump. ‎ The orchestra caught the eye of Paraguayan filmmaker Alejandra Amarilla.She uploaded a short piece of the orchestra to YouTube in 2012，hoping to secure crowdfunding for what would become Landfill Harmonic，a documentary released across the United States this month and promoting the youngsters on a tour of the world's music halls later on.‎ ‎【语篇解读】　本文主要介绍了一个利用垃圾制造的乐器来演奏音乐的管弦乐队的故事。‎ ‎9．What is the best title of the text?‎ A．Youngsters carry tunes from garbage to victory B．A music talent hit the road to the world stage C．A town for music fans D．An orchestra on a global tour 解析：A　标题判断题。根据文章第一段和全文内容可推知，本文主要讲的是一群年轻人利用垃圾制造的乐器演奏音乐并取得成功的故事。‎ 干扰项分析：B项错在本文主题不是讲一个音乐天才走上世界舞台的故事；C项错在音乐粉丝的城镇；D项错在管弦乐队的全球巡演，文章主要讲的是在一个垃圾场上建立起来的管弦乐队受到世界关注的故事，故排除。‎ ‎10．What do we know about Cateura?‎ A．It has raised people's awareness of recycling trash.‎ B．It has caught more attention through the orchestra.‎ C．It recycles more than 1,500 tons of rubbish per day.‎ D．It provides its children with better schooling conditions.‎ 解析：B　细节理解题。根据第一段的第二句“Yet the township...is gaining a reputation as a hothouse for musical talentand for its youth orchestra(管弦乐队)that plays instruments made from garbage”可知，Cateura因其管弦乐队而闻名。‎ 干扰项分析：A项错在提高人们回收垃圾的意识，文章并没有提到；C项错在recycles，根据第二段第一句的“The destination for more than 1,500 tons of waste each day”可知，这个地方每天要堆放1 500多吨垃圾，而不是回收利用这么多垃圾；D项错在给儿童提供更好的就学条件，文章只是提到Favio在Cateura建立了一所青年音乐学校，并没有提到教育条件的改善，故排除。‎ ‎11．Why did Alejandra Amarilla upload a piece of the orchestra to YouTube?‎ A．To assist the youngster with a world tour.‎ B．To collect funding for a documentary.‎ C．To organize carpenters to make instruments.‎ D．To catch the eye of the Paraguay government.‎ 解析：B　细节理解题。根据最后一段的“She uploaded a short piece of the orchestra to YouTube in 2012，hoping to secure crowdfunding for what would become Landfill Harmonic，a documentary”可知， Alejandra Amarilla上传管弦乐队的作品到网上是为了给纪录片筹钱。‎ 干扰项分析：‎ A项错在资助青少年世界之旅，文章中提到纪录片上映后才促成了世界音乐殿堂之旅；C项错在组织木匠来制造乐器，这个是Favio Chavez所做的事，而非Alejandra Amarilla；D项错在吸引Paraguay政府的关注，文章中没有提到。‎ ‎12．What can we learn from Favio Chavez?‎ A．To work in a team weighs more.‎ B．To recycle things is to conserve things.‎ C．To be creative is a quality of a leader.‎ D．To own nothing is no excuse to do nothing.‎ 解析：D　推理判断题。根据第三段Favio Chavez把垃圾变为乐器的事可推知，即使什么也没有也可以有所作为，故选D。‎ 干扰项分析：A项错在强调团队作用，文章中并没有体现；B项错在强调回收利用；C项错在强调创造性对领导人的作用，故排除。‎ ‎ D ‎(2018·安庆二模)‎ ‎ Dragging a sleigh loaded with enough presents for the world's children can be no easy skill. But，since ancient times，the Christmas Eve duty has been performed with distinction by a team of beloved reindeer(驯鹿)．‎ ‎ Soon，however，Santa Claus may have to start looking around for a stronger type of animal，as a new research shows the species is becoming increasingly puny.A 16year survey on the arctic Norwegian island of Svalbard found the reindeer there have declined in weight by an alarming 12 percent.‎ ‎ The reduction in average bodymass is being blamed on global warming. In the research presented lately at a meeting of the British Ecological Society in Liverpool，scientists have explained how rising temperatures are robbing female reindeer of nutrients during important periods of pregnancy.‎ ‎ Snow in Svalbard typically covers the ground for eight months of the year，which，combined with low temperatures，limits grass growth to June and July. But as summer temperatures have increased by around 1.5℃，grass has become more productive，allowing female reindeer to gain more weight by the autumn and therefore to have more babies. However，warmer winters have brought with them greater rainfall which freezes when it settles on the snow. Reindeer can often access the poor food sources beneath the snow by clearing it away with their antlers(鹿角)，but they cannot break through the hard ice. As a result，female reindeer are becoming starved，causing them to abort their babies or give birth to much lighter young.‎ ‎ Despite the findings，reindeer appear to be suffering less from the effect of climate change than some other arctic species. Last week the scientists warned that a third of the world’s polar bears could disappear in the next 40 years.‎ ‎【语篇解读】　本文主要介绍了一项关于驯鹿受气候变化影响的研究。‎ ‎13．Which of the following can replace the underlined word “puny” in Paragraph 2?‎ A．Strong. 　　　　　B．Mature.‎ C．Heavy. D．Weak.‎ 解析：D　词义猜测题。根据第二段第一句“Soon，however，Santa Claus may have to start looking around for a stronger type of animal...”可知，圣诞老人可能很快就得开始寻找一种更加强壮的动物了，由此可推断出驯鹿不像以前那样强壮了，故puny的意思为“瘦弱的”，与weak意思相近。‎ ‎14．Why do female reindeer become fat in autumn?‎ A．The temperature is getting low.‎ B．They give birth to more babies.‎ C．Grass has grown well since summer.‎ D．They often break through the hard ice.‎ 解析：C　细节理解题。根据第四段第二句“But as summer temperatures have increased by around 1.5℃，grass has become more productive，allowing female reindeer to gain more weight by the autumn and therefore to have more babies.”可知，由于夏季气温会升高约1.5℃，牧草更茂盛，使得雌性驯鹿到了秋天会变胖。‎ ‎15．What can we infer from the text?‎ A．Climate change has little effect on reindeer.‎ B．Polar bears suffer more from climate change.‎ C．Reindeer have no trouble finding food in winter.‎ D．Polar bears will disappear in the near future.‎ 解析：B　推理判断题。根据文章最后一段可知，驯鹿受气候变化的影响似乎比其他北极的生物受到的影响要小，且科学家们警告称，全球三分之一的北极熊可能在未来40年内消失。‎ ‎16．What does the text mainly talk about?‎ ‎ A．The Christmas Eve duty will still be carried out by reindeer.‎ ‎ B．Reindeer has decreased in weight owing to global warming.‎ ‎ C．Global warming contributes to more young reindeer.‎ ‎ D．Many arctic species are at the risk of dying out.‎ ‎ 解析：B　主旨大意题。通读文章，本文主要介绍全球变暖导致驯鹿平均体重降低了12%，故选B项。A项表述并非事实；C、D两项偏离主题。‎ Ⅰ.语法填空 ‎(2018·河北省保定三中调考)‎ If you’ve always felt that you look __1__ (attractive) in videos than you do in photographs, you’re not alone. A recent study __2__(do) by researchers at UC Davis and Harvard has found this to be true. It turns out that looking attractive in photos isn’t easy due to __3__ the researchers are calling the “frozen face effect”．‎ In the study university __4__(volunteer) were asked to watch 20 videos of various faces, after __5__they were given 20 stills pulled from the videos they had just watched. When they were then asked to rank the imagery based __6__ attractiveness, the videos consistently ranked higher than the corresponding stills(定格画面)．The researchers even __7__(try) giving the subjects a series of photos shown as a group, but regardless, the video ranked higher——__8__(apparent) we humans like moving faces.‎ Maybe a portrait(人像)photographer’s most prized skill has to do with bringing out __9__ best in people or Photoshop; but in reality it may just be the ability __10__(overcome)the “frozen face effect”．‎ ‎【语篇解读】　哈佛和加州大学戴维斯分校的研究人员发现人们在视频里比在照片上看起来更迷人。也许摄影师的高超技能展现出人类最美的一面。但是事实上可能是因为拥有克服僵化的表情的能力。‎ ‎1．解析：more attractive　考查形容词比较级。句意：如果你认为你在视频里比在照片上看起来更迷人，有这种想法的不只是你一个人。look后面跟形容词，根据than you do in photographs，可以判定用比较级。故填more attractive。‎ ‎2．解析：done　考查非谓语动词。句意：哈佛和加州大学戴维斯分校的研究员的最新研究表明这是真的。根据两个句子之间没有连词，谓语动词是has found可以得知第二个动词用非谓语形式，研究和做是被动关系。故填done。‎ ‎3．解析：what　考查从句引导词。句意：在照片中看着不迷人是因为僵硬的表情引起的。介词to后面的宾语从句中call缺少宾语。故填what。‎ ‎4．解析：volunteers　考查名词。句意：在研究中大学生志愿者被要求观看20个不同表情的视频。Were可以判断出主语用复数形式。故填volunteers。‎ ‎5．解析：which　考查关系代词。句意：在这之后给志愿者们从视频中截取的图片。定语从句指代前面整件事，介词后只能用which。故填which。‎ ‎6．解析：on/upon　考查介词。句意：当志愿者被要求根据迷人程度排列一下时，视频总是比定格画面顺序朝前。“以……为基础”是base...on/upon。此处填介词。故填on/upon。‎ ‎7．解析：tried　考查动词时态。句意：研究员甚至尝试要求志愿者按照照片排列，但是尽管这样，视频还是排列靠前。本段做的实验是过去的事情，用一般过去时。故填tried。‎ ‎8．解析：apparently　考查副词。句意：很明显，我们喜欢移动中的面孔。副词修饰整句话。故填apparently。‎ ‎9．解析：the　考查冠词。句意：也许摄影师的高超技能展现出人类最美的一面。此处表示最高级the best，故填the。‎ ‎10．解析：to overcome　考查非谓语动词。句意：但是事实上可能是因为拥有克服僵化的表情的能力。做某事的能力ability to do，用不定式结构作定语。故填to overcome。‎ Ⅱ.短文改错 ‎(2018·哈师大附中模拟)‎ ‎ I've learnt from the notice that you're looking for an English editor for us school paper. I'm written this letter to apply for the position.‎ ‎ I'm Li Hua，Senior Three student in our school. In my view，I met your requirements. For one thing，I'm willing to devote some of my spare time to serve others. For another，I'm good at both English or Fine Arts. I’m either skilled in using computers. I would be glad if you could offer to me an opportunity for an interview.‎ ‎ I'm looking forward to your kindly reply at your earliest convenient.‎ 答案：‎ ‎ I've learnt from the notice that you're looking for an English editor for school paper. I'm this letter to apply for the position.‎ ‎ I'm Li Hua， Senior Three student in our school. In my view，I your requirements. For one thing，I'm willing to devote some of my spare time to others. For another，I'm good at both English Fine Arts. I’m skilled in using computers. I would be glad if you could offer ‎ to ‎ me an opportunity for an interview.‎ ‎ I'm looking forward to your reply at your earliest .‎ ‎1．解析：us→our　school paper为名词短语，其前应用形容词性物主代词。故将us→our。‎ ‎2．解析：written→writing　write与主语I之间为主动关系，因此，不用被动语态。故将written改为writing，表示正在进行。‎ ‎3．解析：在Senior前加a　Senior Three student作Li Hua的同位语，泛指“一名高三学生”，因此其前应用不定冠词a。‎ ‎4．解析：met→meet　此处表达“我符合您的要求”，阐述的是客观事实，应用一般现在时。故将met→meet。‎ ‎5．解析：serve→serving　devote time to...短语中to是介词，其后如果接动词，应用动名词形式。故将serve→serving。‎ ‎6．解析：or→and　both...and...为固定短语，意为“两者都”。故将or→and。‎ ‎7．解析：either→also　表示“也”，用在句中，应用also; either常用于否定句句末。故将either→also。‎ ‎8．解析：删除offer后的to　offer sb. sth.是固定搭配，意为“提供某人某物”。故删除to。‎ ‎9．解析：kindly→kind　reply为名词，应用形容词修饰。故将kindly→kind。‎ ‎10．解析：convenient→convenience　your earliest为“形容词性物主代词＋形容词”，其后应用名词。故将convenient→convenience。‎ Ⅲ.书面表达 ‎(2018·湖南长沙高三模拟)‎ 假定你是李华，在一个英文网络论坛上，你看到一个名叫Mike的中学生发帖(post)寻求帮助。请根据帖子内容、写作要点和要求回帖。‎ Hi，everyone，‎ ‎ I'm 18 years old and I'm going to a university in Beijing this autumn.My parents insist on going with me to help me with my daily life. But I think I can manage it all by myself. How can I make them change their ideas?‎ ‎ 写作要点：‎ ‎ 1.告诉Mike要理解父母；‎ ‎ 2.给Mike提出解决问题的具体建议。‎ ‎ 注意：1.词数100左右(不含已写好的部分)；‎ ‎ 2.可以适当增加细节，以使行文连贯。‎ Hi，Mike，‎ ‎ As a student of your age，I understand your situation.________________________________________________________________________‎ ‎________________________________________________________________________‎ ‎________________________________________________________________________‎ 答案：‎ Hi，Mike，‎ ‎ As_a_student_of_your_age，I_understand_your_situation.I think it is wise of you to go all by yourself.But you need to deal with your problem cautiously.You'd better avoid hurting the feelings of your parents.Here are some of my suggestions.‎ As your parents，they may have many reasons to go with you.This is your first time to be far away from home for so long，and they surely have some worries and wish to see everything go well.So have a talk with them peacefully and listen patiently.‎ And then，express your thanks for all their love and care.Persuade them you can manage everything well this time just as you did many times in the past.Remember to invite them to Beijing when you have already settled down.I am sure they will understand you and take your idea into consideration.‎ All the best.‎ Yours sincerely，‎ Li Hua