What he has learned through practice before him a lot in his future work.A. helpingB. hel

问题补充：

What he has learned through practice before him a lot in his future work.

A. helping

B. helped

C. it helps

D. will help

答案：

A. helping

B. helped

C. it helps

(答案→)D. will help

解析：before这里是副词,不是介词,也不是连词,所填词实际是谓语动词.