问题 选择题
对于光的衍射现象,下述定性分析中错误的是(   )

A.光的衍射是光在传播过程中绕过障碍物继续传播的现象

B.光的衍射否定了光的直线传播的结论

C.光的衍射现象为光的波动说提供了有力的证据

D.光能发生明显衍射的条件是光的波长与孔或障碍物尺寸可比拟

答案

答案:B

阅读理解

阅读理解

        What does an astronaut (宇航员) eat in space? This is a question that

will puzzle many, as people rarely think of that. In the early space-travel

years, astronauts ate dehydrated (脱水的) foods that were eaten through

straws(吸管). In today's space-age, the food that they eat is totally different.

They eat food in the same way as people do on Earth.

        Astronauts are able to prepare and eat a variety (多样化)of foods in

space. Some can be eaten in their natural form, like fruits; while some need to add water, like noodles. However, there are no refrigerators, so the food has

to be prepared and eaten without being Stored for a long time. When the

astronauts are hungry, they simply eat the food by opening the food ackages and with a fork, knife, and spoon.

       Just like people on Earth, astronauts also eat three meals a day which

include breakfast, lunch and dinner. Sometimes they also eat snacks. The US

space agency NASA has found out that an astronaut's diet reduces(减少) by

about 70% on a space mission, though he has a wide range of foods to

choose from like nuts, chicken, beef, seafood, and candies. Drinks in the

spaceship include coffee, tea, juices, and lemonade.

       Astronauts can also request a particular food that they would like to have in space. Scientists are always experimenting and trying out different space

foods that can be offered to astronauts when on space missions.

1.In the early space-travel years, astronauts  ___________.

A.ate the same food as on Earth

B.drank milk through Straws

C.ate dehydrated food                

D.ate with a fork; knife; and spoon

2.In today's space-age, astronauts  __________

A.can only eat fruit and noodles

B.can't eat anything in a natural way

C.can use the refrigerators to store the food

D.can eat many kinds of food like on Earth.

3.The US space agency NASA has found out that ________in space.

A.an astronaut can eat more than on Earth.

B.an astronaut eat less than on Earth

C.an astronaut eat as much as on Earth

D.an astronaut doesn't have to eat food at all.

4.Astronauts eat three meals a day in space, and they can also __________.

A.cook for themselves    

B.drink some beer

C.smoke      

D.eat snacks

5.Scientists are always experimenting and trying out different space foods

that can be offered to astronauts  ________.

A.when they exercise                  

B.when they are sick

C.when on space missions                

D.when they relax themselves

问答题