Some people say that the best way to reduce the size of your waist is to do stomach exercise. Many people believe that when specific muscles are exercised, the fatty tissues (组织) in the immediate area are burned up. The truth is that exercise burns fat from all over the body and not from one specific area. Of course, if you reduce the fat throughout your body, you will certainly see results around your waist too.
Some people believe that you need to exercise twice a week in order to keep a sufficient level of physical fitness. However, studies directed by American scientists show that unexercised muscles lose their strength very quickly. Within 48 to 72 hours, you must use the muscles again to reestablish (重建) the good physical effects. And what does that mean to you? American scientists concluded that while daily exercise is most helpful, exercising every other day or three days a week will keep a sufficient level of physical fitness.
Is it true that you burn more calories running one mile than walking the same distance? The answer is no. The truth is that you use the same amount of energy whether you walk or run the mile, since in both cases you are moving the same weight the same distance. The speed does not matter. Of course, if you run rather than walk for 30 minutes, you will cover more distance, and therefore burn more calories.
If your breathing doesn’t return to normal within 5 minutes after you finish exercising, you have exercised too much. Five minutes or so after exercising, your breathing should be normal, your heart shouldn’t be beating loudly, and you shouldn’t be tired.
If you want to reduce the fat around your waist, you should ____.

A．do stomach exercise	B．exercise the waist
C．exercise all the muscles of your body	D．run fast for 30 minutes

From the second paragraph, we learn that ____.  

A．we only need to exercise twice a week

B．we should exercise three times a week

C．muscles lose their strength after 48 hours

D．we should exercise every other day, or three days a week

It can be inferred from the third paragraph that _________ .  

A．you will lose more weight running one hour than walking one hour

B．whether you run one mile or walk the same distance, you use the same amount of energy

C．you will lose more weight running one mile than walking the same distance

D．both A and B

If you have exercised too much, _______. 

A．your breathing will take longer than 5 minutes to return to normal after you finish exercising

B．your breathing will return to normal within 5 minutes after finishing exercising

C．your heart will not be beating loudly

D．you will be too tired to move

This passage tells us that _________.  

A．it is better to do more running than walking

B．the more exercise you do, the healthier you will be

C．the unexercised muscles must be used again within 48 to 72 hours

D．in order to lose weight, you have to run fast