问题补充：
Why should we learn to swim?
Firstly, swimming is a good exercise for our health. Indeed doctors say it is the best exercise, because in swimming all the muscles of the body are used.
Secondly, swimming gives great pleasure. How nice it is, on a hot dusty day in summer, to take off one’s clothes and dive into the cool water of a rive or the sea, and to swim and float until one feels enough.
Thirdly, swimming may sometimes mean all the different between life and death, we never know when we may be in danger from water. We got on a voyage, and the ship in wrecked; we go for a pleasure sail on a lake and the boat turns over; we slip as we are walking along the bank of a river, and half in the water. If we can swim, we have chance for saving our own lives, but if we cannot swim, we are pretty certain to be drowned. So for our own safety, we should learn to swim.
Lastly, if we can swim, we may be able to save other people from drowning. How sad it is to see a friend drowning before our eyes while we cannot help just because we cannot swim.
11.Who says that swimming is the best exercise? .
A. Farmers B. Dentists C. Fishermen D. Doctors
12.When swimming, .
A. We don’t move at all B. all the muscle of the body are used
C. we move our legs only D. we drink lots of seawater into our stomach
13.Swimming .
A. gives great pain B. gives no pleasure
C. gives much pleasure D. does harm to the body
14.If we can swim, .
A. we are no longer humans, but fish B. we shall be drowned one day
C. we have a chance of saving our own lives D. we can’t walk any more
15.If we can swim, .
A. we may be able to help others from drowning
B. we can’t save others from drowning
C. it is pretty danger certain that we will get drowned
D. there is a great danger when we fall into the waterD
答案：
(答案→)D
解析：
【小题1】根据swimming is a good exercise for our health. Indeed doctors say it is the best exercise,可知是医生说的，故选D。
【小题1】根据because in swimming all the muscles of the body are used.可知选B。
【小题1】根据swimming gives great pleasure.可知选C。
【小题1】根据swimming may sometimes mean all the different between life and death,及下文描述可知会游泳有时可能会拯救自己，故选C。
【小题1】根据Lastly, if we can swim, we may be able to save other people from drowning.可知选A。
