My mother often tells me my classmates when they need.A. helpB. to helpC. helpingD. help

问题补充：

My mother often tells me my classmates when they need.

A. help

B. to help

C. helping

D. helps

答案：

A. help

(答案→)B. to help

C. helping

D. helps

解析：tell sb todo sth告诉某人去做某事。根据句意：我的妈妈经常告诉我要帮助需要帮助的同学。