Question

– Do you know who cleaned the blackboard, Tina? -- Yes. John _____. A. do &nbs...

– Do you know who cleaned the blackboard, Tina? -- Yes. John _____. A. do B. does C. did

Answer 1

C

对于问题的简短回答可用人称+助动词，本题的关键词是cleaned，故本题用助动词did，故本题选C。