单项选择 ( )1.Are you good at A.swim B.swimming C.to swim D.swa

单项选择 ( )1.Are you good at A.swim B.swimming C.to swim D.swa
单项选择 ( )1.Are you good at A.swim B.swimming C.to swim D.swa

单项选择 ( )1.Are you good at A.swim B.swimming C.to swim D.swa
B
at是介词

B

正确：B （介词at+doing)

swimmming .be good at doing sth

be good at doing sth.擅长做某事
B（介词后加动词ing）