---Who cleaned the blackboard yesterday Dick?---John .A. cleanB. doesC. didD. is

问题补充：

---Who cleaned the blackboard yesterday, Dick?

---John .

A. clean

B. does

C. did

D. is

答案：

A. clean

B. does

(答案→)C. did

D. is

解析：句意：--Dick，昨天是谁清扫的黑板？--John做的。分析上文的工作是过去动作，下文对同样的动作要用助动词来代替，体现为过去时用did来进行替换。故选C