阅读理解

    Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin color.

    The gene comes in two versions, one of which is found in 99 percent of Europeans. The other is found in 93 to 100 percent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

    Scientists have changed the color of a dark-striped zebra-fish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebra-fish skin color is determined by pigment cells, which contain melanin (黑色素). The number, size and darkness of melanin per pigment cell determine skin color.

    It appears that, like the golden zebra-fish, light-skinned Europeans also have a mutation (变异) in the gene for melanin production. This results in less pigmented skin.

    However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebra-fish genes.

    Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun (太阳光紫外线), which can cause skin cancer.

    But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

    Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.

    The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin color without damaging it like chemical treatment did on Michael Jackson.

He decided to i England and land his troops at Liverpool.

The old man had one son and two daughters,     treated him well,     made him very sad.

We  (arrive) there before it began to rain.

含有1mol HNO₃的稀硝酸分别与不同质量的铁粉，所得氧化产物a、b与铁粉物质的量关系如图所示．下列有关判断正确的是（   ）

Scientists are convinced _____ the positive effect of laughter _____ physical and mental health.

向含CuCl₂和HCl的100g混合溶液中，逐滴加入溶质质量分数为10%的NaOH溶液，参加反应的NaOH溶液质量与生成沉淀质量关系如图，仅考虑沉淀为Cu（OH）₂则下列说法不正确的是（　　）

阅读理解

    Fireworks(烟花) can add excitement to all kinds of celebrations. However, fireworks can be very dangerous if not handled and used properly. To reduce the risks associated with a firework display, adults need to be aware of firework safety rules, and so do children who are watching. There are some basic rules to follow.

    Make sure you are using only legal fireworks. There are reasons for the banning of certain fireworks, such as safety concerns. Explain to your children the dangers of fireworks and give them a written emergency number to call in case something goes wrong, along with the address of your firework display. Fill a bucket with water and have a fire extinguisher(灭火器)on hand.

    Never allow your children to light the fireworks. This should be done only by a responsible adult. Move all children to a safe distance from the fireworks and have them remain there until the show is finished. Make sure the fireworks are set off pointing to the sky and not to the side. To prevent injuries, it is important that the fireworks are never thrown or held in a person's hands while being lit. Because fireworks are very loud, you may want to place earmuffs(耳罩)on young children.

    When the firework display is finished, there will be a lot of debris(残骸)to pick up. If there are any fireworks that do not light properly, wait at least fifteen minutes before you get close. Place the faulty fireworks and the firework debris into a bucket of water. This will ensure that none of them will relight. Put all unused fireworks and lighters far out of the reach of children so they can't try to light them. Remember that safety comes first!

分别燃烧等物质的量的下列各组物质，其中消耗氧气的量相等的是（   ）

①C₂H₂与C₂H₄O   ②C₄H₈与C₆H₁₂O₆   ③C₇H₈与C₆H₁₂ ④HCOOCH₃与CH₃COOH．

My roommates disagreed and I was caught in .

Next Friday afternoon, I will be having a class in (工业的) history.

She was still waving as the train (消失) from view.

一定量的MnO₂与xmL10mol/L的盐酸共热制取氯气，在标准状况下产生2.24L．则x的值应为（　　）

He is studying in another city. He keeps in touch his family by phone and e-mail.

We are not prepared  (accept) these conditions.

We must r some of this corn for next year's seed.

下面文段有四处语病，请指出其序号并做修改，使语言表达准确流畅。

①表情包作为互联网时代的新兴产物，②是一个社会心理变迁的风向标。③一方面表情包带来交流便捷的优点，④另一方面其本身带有娱乐性，能帮助人们减轻压力，排遣负面情绪。⑤近年来，随着表情包行业的逐渐成熟，表情包的商业潜力被充分挖掘，⑥走上产业化发展之路。⑦成熟的表情包形象，可以被制作成公仔、毛毯、手机壳、充电宝等周边产品售卖，⑧甚至开发成动漫、游戏和电影中的形象。

I just wonder   that makes him so excited.

相同状况下，1.12L乙烷和丁烷的混合物完全燃烧需O₂ 4.76L，则混合气中乙烷的体积分数是（　　）

阅读下面的材料，根据要求写作。

2020年，“高校奖励新生一个人报到”的话题冲上热搜，起因是某大学特别设置并颁发了“独立新生奖”。凡是无家长陪同报到的学生，即可获得奖励。消息一出，引发了不少网友、新生和家长的热议。有的对学校鼓励学生实现自我突破、树立自我管理意识的做法表示支持；有的认为大学生当然应该独立，但学校“一刀切”的做法会带来诸多不便；还有的认为有没有家长陪同报到与孩子独立与否并不直接相关，设立奖项宣扬这种行为没有必要。

请你从“网友、新生和家长”中任选一个身份，给《中国青年报》“观点”栏目的编辑写一封信，表达你对这个事件的看法。

要求：结合材料，选好角度，确定立意，自拟标题；不要套作，不得抄袭；不得泄露个人及学校信息；不少于800字。