问题 选择题

人体血红蛋白中含有Fe2+,如果误食亚硝酸盐,会使人中毒,因为亚硝酸盐会使Fe2+转变为Fe3+,生成高铁血红蛋白而丧失与O2结合的能力。服用维生素C可缓解亚硝酸盐的中毒,这说明维生素C具有[ ]

A、酸性

B、碱性

C、氧化性

D、还原性

答案

答案:D

阅读理解

Skin-diving(潜水) is a new sport today. This sport takes you to a wonderful new world. It’s like a visit to the moon! When you’re under the water, it’s easy for you to climb big rocks(岩石) because you aren’t heavy any more.

Everything is blue and green under the water. During the day, there’s enough light(光). When fish swim nearby, you can catch them with your hands.

When you have tanks of air(氧气罐) on your back, you can stay in deep water for a long time. But you must be careful, when you dive in deep water.

It’s the most interesting part of this sport to catch fish. There are most uses for skin-diving, too. You can clean ships without taking them out of the water. You can get many things from the deep sea.

Now you see that skin-diving is both useful and interesting.

小题1: Skin-diving can take you to ___________.

A.the moon

B.be in danger

C.mountains

D.the deep sea小题2:You can climb big rocks under water because _________.

A.you are stronger

B.the fish nearby help you

C.you aren’t as heavy as on the land(陆地)

D.there is a lot of light小题3: Under water, a skin-diver _________ in the day-time.

A.can see anything clearly

B.can’t see anything clearly

C.can see nothing

D.can see only fishes小题4:With a tank of air on your back, you can _________.

A.catch fish very easily

B.stay under water for a long time

C.be in safe place

D.have more fun小题5: Which of the following is NOT true?

A.Skin-diving is a new sport

B.Skin-diving is like visiting the moon

C.The only use of skin-diving is to have more fun.

D.Skin-diving is both interesting and useful

问答题 简答题