[单项选择]

阅读下面的短文，回答以下问题。
①细菌和病毒都是可以致病的微生物，但它们的特征区别很大。细菌虽然小，要在光学显微镜下才能看得见，但它除了拥有生命的基本单位核酸之外，还有一大套赖以生存的配套设施。包括作为居住“公馆”的细胞壁，储存营养物质的“仓库”，以及进行新陈代谢的“化工车间”。依靠这些，细菌能够摄取外界的物质并加工成需要的能量。
②而病毒就更小了，也可怜得多，且不奢谈“库房”和“车间”，就连作为保护外壳的“茅草房”也没有。实际上它只有一个分子大小，用电子显微镜才能看得见。整个家当也只是一条表示生命的核酸而已。如果拿人来做比喻，细菌最起码也有条裤子，有只讨饭碗，有根打狗棒。所以细菌虽然必须在人体内部的良好环境中才能繁殖，但处在恶劣环境中仍能生存较长的一段时间。而病毒则像个刚出生的婴儿，除了它的生命和一张吃奶的嘴外便一无所有，毫无独立生存的能力。因而病毒只能寄生在人或动物的细胞内部，靠“窃取”细胞里的现成营养才能生存。一旦被排出体外，病毒就活不了几小时。
③大部分抗生素对细菌起作用，是因为抗生素可以抑制细胞繁殖，干扰它们形成新的遗传结构或者细胞壁。而正因为病毒只能寄生在别人的细胞内，自己不能完成这些生化反应，所以抗生素对病毒全无作用。
④结构这样简陋的病毒算不算是生命这是个值得讨论的问题。生命必须具备的条件有两条：能进行新陈代谢和自我复制。从这点来说病毒具备了生命的重要特征。但它又不是完整的生命，因为所有生物体的生命特征都寓藏于DNA的双螺旋链中，唯独病毒没有双螺旋，而只有一条单链，有时还不是DNA而是RNA，所以病毒只具备了部分的生命特征。因而病毒不属于生物界共同的生命形式，或者说只是一种残缺不全的生命形式。
⑤病毒的生存能力既然这么弱，为什么还会那样猖獗呢例如埃博拉的感染力极强，病死率可达80%。实际上大多数病毒远没有那么可怕，有的也不会使人得病。冠状病毒本来致病的能力并不强，问题在于“变种”上。变异的病毒和原来的不同了，它可能是无害的，但也可能变成“杀伤力”更
A. 只能寄生在人或动物的细胞内部
B. 体积只有一个分子大小，用电子显微镜才能看得见
C. 具备了生命特征，但不属于生物界共同的生命形式
D. 虽然生存能力极弱，但仍然会发生变异

[单项选择]

阅读下面的短文，回答以下问题。
①细菌和病毒都是可以致病的微生物，但它们的特征区别很大。细菌虽然小，要在光学显微镜下才能看得见，但它除了拥有生命的基本单位核酸之外，还有一大套赖以生存的配套设施。包括作为居住“公馆”的细胞壁，储存营养物质的“仓库”，以及进行新陈代谢的“化工车间”。依靠这些，细菌能够摄取外界的物质并加工成需要的能量。
②而病毒就更小了，也可怜得多，且不奢谈“库房”和“车间”，就连作为保护外壳的“茅草房”也没有。实际上它只有一个分子大小，用电子显微镜才能看得见。整个家当也只是一条表示生命的核酸而已。如果拿人来做比喻，细菌最起码也有条裤子，有只讨饭碗，有根打狗棒。所以细菌虽然必须在人体内部的良好环境中才能繁殖，但处在恶劣环境中仍能生存较长的一段时间。而病毒则像个刚出生的婴儿，除了它的生命和一张吃奶的嘴外便一无所有，毫无独立生存的能力。因而病毒只能寄生在人或动物的细胞内部，靠“窃取”细胞里的现成营养才能生存。一旦被排出体外，病毒就活不了几小时。
③大部分抗生素对细菌起作用，是因为抗生素可以抑制细胞繁殖，干扰它们形成新的遗传结构或者细胞壁。而正因为病毒只能寄生在别人的细胞内，自己不能完成这些生化反应，所以抗生素对病毒全无作用。
④结构这样简陋的病毒算不算是生命这是个值得讨论的问题。生命必须具备的条件有两条：能进行新陈代谢和自我复制。从这点来说病毒具备了生命的重要特征。但它又不是完整的生命，因为所有生物体的生命特征都寓藏于DNA的双螺旋链中，唯独病毒没有双螺旋，而只有一条单链，有时还不是DNA而是RNA，所以病毒只具备了部分的生命特征。因而病毒不属于生物界共同的生命形式，或者说只是一种残缺不全的生命形式。
⑤病毒的生存能力既然这么弱，为什么还会那样猖獗呢例如埃博拉的感染力极强，病死率可达80%。实际上大多数病毒远没有那么可怕，有的也不会使人得病。冠状病毒本来致病的能力并不强，问题在于“变种”上。变异的病毒和原来的不同了，它可能是无害的，但也可能变成“杀伤力”更
A. “变异”发生在病毒的遗传物质上，因而具有这种遗传物质的“变种”在没有接触过它的人群中会为患甚大
B. 变异具有不断反复的特点，而且每一次反复都会给新病毒带来对人体有害的遗传物质
C. 因为变异后病毒的杀伤力不会次第增大，所以变异的病毒可能“杀伤力”更大，但也可能无害
D. 病毒“杀伤力”的大小取决于人群的免疫力，当人群中有足够多的人产生了抗体之后，这种病毒对人类的威胁也就小得多了

[单项选择]
根据下面短文回答下列问题。
There were three professors at the railway station. They were deep in conversation. The train had just arrived, but they didn’t see it. Then the guard (列车员) shouted (喊道), "Take your seats, please!"
The professors heard the shouts and rushed for the train. Two of them got on the train before it moved. The third one was left behind. He looked sad. One of his students was at the station. He told the professor, "It wasn’t too bad, sir. Two out of three got on the train."
But the professor said, "It was my train. My two friends only came to say goodbye./

The three professors didn’t see the train, because ______
A. They were deep in the water
B. They were wearing glasses, and couldn’t see clearly
C. They were deep in talking

[单项选择]根据下面短文回答下列问题。
Most American families have one or two parents and one or two children each.
Children in the US will leave their parents’ home when they grow up. They usually live far from their parents because they want to find good jobs. They often write to their parents or telephone them. And they often go to visit their parents on holidays.
Parents usually let their children choose their own jobs. Americans think it is important for young people to decide on their lives by themselves.
Children are asked to do some work around their home. And in many families, children are paid for doing some housework so that they learn how to make money for their own use.
Children in America will not live with their parents all their lives.
[A] True.
[B] False.

[单项选择]
根据下面短文回答下列问题。
Eskimos live in the northern (北部的) part of North America, from Alaska to Greenland. In that area, winter is nine months long. There is snow and ice everywhere. Not long ago the Eskimo family lived in a house made of ice and hard snow. It was called an "igloo". The igloo was heated(加热) with oil lamps. A hole is made in the roof for smoke or smell to go out. Today they live in houses made of wood and iron. But sometimes they will live for a while in an igloo when they go hunting (打猎).
Many years ago, only the Eskimos lived in this land. The Eskimos had believed that they were the only people in the world. They called themselves "Inuit". That means the people. Later when the American Indians (印第安人) met the Inuit, they called them Eskimos. That Indian word means "eaters of raw meat".

The word "igloo" means ______.
A. the house made of snow and ice
B. the people who live in Alaska
C. the building made of wood

[单项选择]
根据下面短文回答下列问题。
Many people earn their living with their hands. Ed earns his living with his feet! His story begins in a small town in Brazil(巴西). His father and mother were very poor. Seven people lived in their small house. He had no place to play but in the street.
Ed’s father often played soccer, a game like football. Little Ed wanted to play it too. So his father made a small ball for him to kick. At last Ed learned to kick a real soccer ball. By the time he was 11, he played soccer very well.
In his first big game, Ed helped his team win by seven points. He made four of the seven points! And he was only 15 years old.

There were seven people lived in their house, so he played soccer ______.
A. in the street
B. in their small house
C. in the big game