what is your brother able--------?A. to doB. doC. to doingD. does

问题补充：

what is your brother able--------?

A. to do

B. do

C. to doing

D. does

答案：

(答案→)A. to do

B. do

C. to doing

D. does

解析：be able to do表示能够做某事，故本题选A。