Saying always has less difficulty than .A. doneB. doingC. to doD. having done

问题补充：

Saying always has less difficulty than .

A. done

B. doing

C. to do

D. having done

答案：

A. done

(答案→)B. doing

C. to do

D. having done

解析：doing和saying相对照，都是动名词。