Who was it that let the cry of surprise.A. inB. outC. downD. alone

问题补充：

Who was it that let the cry of surprise.

A. in

B. out

C. down

D. alone

答案：

A. in

(答案→)B. out

C. down

D. alone

解析：let out意思是：放走，释放；泄露，放出，发出。