There are some boys in the river.A. swimmingB. to swimC. are swimmingD. is swimming

问题补充：

There are some boys in the river.

A. swimming

B. to swim

C. are swimming

D. is swimming

答案：

(答案→)A. swimming

B. to swim

C. are swimming

D. is swimming

解析：A 考查固定句型。There be +名词 +doing sth.“有一些......正在做某事。”故选A。