My mother is always warning me when I go out “Don’t get off the bus it is stopping.” A.

问题补充：

My mother is always warning me when I go out, “Don’t get off the bus it is stopping.”

A. until

B. before

C. while

D. after

答案：

A. until

B. before

(答案→)C. while

D. after

解析：本题考查连词的用法。由语境分析可知，此处表达的意思为“在公共汽车将要停止的过程中不能下车”，能表达此意的连词只有while，表示“在……过程中”