He was about to tell me the secret someone patted him on the shoulder.A. asB. untilC. whil

问题补充：

He was about to tell me the secret someone patted him on the shoulder.

A. as

B. until

C. while

D. when

答案：

A. as

B. until

C. while

(答案→)D. when

解析：在主句是be about to do sth.的情况下，从句用when引导。