-Who helped Mum wash the dishes yesterday? ---Helen .A. doesB. doC. didD. was

问题补充：

---Who helped Mum wash the dishes yesterday? ---Helen .

A. does

B. do

C. did

D. was

答案：

A. does

B. do

(答案→)C. did

D. was

解析：句意：谁昨天帮妈妈洗碗了？Helen帮的。Did指代前文的动词helped，因为描述的是过去的事情，所以用did，故选C。