Tom was about to close the windowhis attention was eaught by a bird.A. whenB. ifC. andD. t

问题补充：

Tom was about to close the windowhis attention was eaught by a bird.

A. when

B. if

C. and

D. till

答案：

(答案→)A. when

B. if

C. and

D. till

解析：固定搭配be about to do sth when… 刚要做某事这时…。 句意：汤姆刚要关窗户这时一只鸟吸引了他的注意。