选择正确的答语。

(      ) 1.  What do you do after supper?

(      ) 2.  What colour are the leaves?

(      ) 3.  What is exercise?

(      ) 4.  How many minutes do you play basketball every day?

(      ) 5.  How often do you eat donuts?

A.  About twenty minutes.

B. Twice a week.

C.  I do my homework after supper.

D.  They are green.

E.  Playing ping-pong is exercise

某运动员完成400米跑比赛后，静止站立休息时，突然感觉头昏眼黑并发生晕倒，试结合运动实践分析其可能的生理学原因及处置方法。