There are some children in the room.A. singingB. singC. are singingD. to sing

问题补充：

There are some children in the room.

A. singing

B. sing

C. are singing

D. to sing

答案：

(答案→)A. singing

B. sing

C. are singing

D. to sing

解析：本题考查的动词的现在分词短语作后置定语，故选A