I have only one uncle I can turn to for help.A. thatB. whichC. whomD. /

问题补充：

I have only one uncle, I can turn to for help.

A. that

B. which

C. whom

D. /

答案：

A. that

B. which

(答案→)C. whom

D. /

解析：这是定语从句，从句中缺宾语，前面的先行词是指人。所以选C。