Jumping out of train running at a speed of 200 kilometers per hour is quite dangerous p

问题补充：

Jumping out of train running at a speed of 200 kilometers per hour is quite dangerous practice.

A. /; the

B. /; a

C. a; a

D. the; the

答案：

A. /; the

B. /; a

(答案→)C. a; a

D. the; the

解析：前一空表示某一列火车，表示泛指，所以用a，第二空说，这是一次危险的经历，所以也是用a。