问题 单项选择题 A1型题

氟尿嘧啶的抗恶性肿瘤()

A.阻碍DNA合成

B.阻碍蛋白质合成

C.阻碍纺锤丝形成

D.与DNA联结而破坏DNA的结构和功能

E.与DNA结合而阻碍RNA转录

答案

参考答案:A

单项选择题 A1/A2型题
阅读理解

阅读理解。

Read and answer the following questions.

      The United States is one of the biggest countries in the world. It has all sorts of geography, from deserts

to beaches, mountains to flatlands. These conditions help create all sorts of weather: mild, moderate and

extreme. Sometimes all in one day! In the summer, some areas get very hot and the air is very wet. But others

have dry air, so the heat does not feel so bad.

     In the winter, parts of the country get cold and snowy while others stay warm and sunny. This is the

difference between, for example, New York City on the East Coast and Los Angeles on the West Coast. Yet

even the East Coast has its warm places in winter, like Florida.

     The oceans affect weather along the coasts. The Pacific coast has smaller temperature changes and calmer

conditions than along the Atlantic.

     Alaska and Hawaii are the only states not connected to the forty-eight mainland states. Alaska is in the

Arctic area, so it gets very cold. Hawaii, out in the Pacific, is warm all year long.

     Weather in the central and northeastern parts of the country is affected by cold air from Canada and warm

air from the Caribbean. Conditions can change quickly.

     Hurricanes are ocean storms that strike mainly in the Southeast. The hurricane season is, officially, June

through November. Tornadoes are a risk across the country. These are locally severe windstorms. They

generally happen in spring and summer.

      In fact, March eighteenth happens to be the eightieth anniversary of the most deadly tornado in United

States history. The nineteen twenty-five"Tri-State Tornado" hit parts of Missouri, Illinois and Indiana. The

National Weather Service says the horrible twister killed nearly seven hundred people.

1. Why does America have all sorts of weather? (回答词数不超过8个)

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2. What is the difference in weather between Alaska and Hawaii?(回答词数不超过7个)

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3. What makes the weather conditions change quickly in the central and northeastern parts of the US?

(回答词数不超过10个)

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