.I have just come in to see if I can be any assistance to them.A. withB. onC. atD. of

问题补充：

.

I have just come in to see if I can be any assistance to them.

A. with

B. on

C. at

D. of

答案：

A. with

B. on

C. at

(答案→)D. of

解析：可联系答.案.网客服索取。