.I was about to get on the bus my wife phoned me to back home at once.A. whenB. whileC. un

问题补充：

.I was about to get on the bus my wife phoned me to back home at once.

A. when

B. while

C. until

D. after

答案：

(答案→)A. when

B. while

C. until

D. after

解析：考查固定句型。Be about to do sth when…正要做某事在这时…(发生了意料之外的事情)；句意：我正要上车在这时我的妻子打电话给我要我立刻回家。故A正确。