My brother and I had fun in the river this summer vacation.A. swam B. swimming C. swim D.

问题补充：

My brother and I had fun in the river this summer vacation.

A. swam

B. swimming

C. swim

D. to swim

答案：

A. swam

(答案→)B. swimming

C. swim

D. to swim

解析：考查非谓语动词。句意:这个暑假我的哥哥和我在河中游泳玩的很高兴.have fun doing sth做某事很高兴,现在分词状语表示伴随性动作,和句子主语是主谓关系,故选B。