问题 选择题

下列哪种鳍控制鲫鱼身体前进的方向                           (   )

A.胸鳍

B.腹鳍

C.尾鳍

D.背鳍

答案

答案:C

题目分析:

A.胸鳍起平衡作用,故A不符合题意。

B.腹鳍起平衡作用 ,故B不符合题意。

C.尾鳍可以决定运动方向,又能同尾部一起产生前进的推动力 ,故C符合题意。

D.背鳍有保持鱼体侧立,对鱼体平衡起着关键作用,故D不符合题意。

单项选择题

More and more people like bicycling and it is no surprise. It is fun, healthy and good for the environment. Maybe that’s why there are 1.4 billion bicycles and only 400 million cars on roads worldwide today. Bikes can take you almost anywhere, and there is no oil cost!

Get on a bicycle and ride around your neighbourhooD. You may discover something new all around you. Stopping and getting off a bike is easier than stopping and getting out of your car. You can bike to work and benefit (受益) from the enjoyable exercise without polluting the environment. You don’t even have to ride all the way.

Folding (折叠) bikes work well for people who ride the train. Just fold the bike and take it with you. You can do the same on an airplane. A folding bike can be packed in a suitcase. You can also take a common bike with you when you fly. But be sure to look for information by getting on airline websites. Not all airlines are bicycle-friendly to travelers.

Health Benefits of Bicycling.

·It helps to prevent heart diseases.

·Bicycling helps to control your weight.

·A 15-minute bike ride to and from work three times a week burns off five kilos of fat in a year.

·Bicycling can improve your mood (心情).

·Exercise like bicycling has been shown to make people feel better, more relaxed and self-confident.

·Bicycling is healthier than driving.

If you travel with a folding bike, you can fold it and ().

A. get out of the car

B. take it onto a train

C. put it in your purse

D. go on airline websites

单项选择题