【题目】They're __________ very fast. ( )
A.runing B.running C.to run D.runs
【答案】B
【解析】
句意:他们正跑得很快。由句子可知时态为现在进行时,结构是be doing,run的现在分词是running,故答案为B。

【题目】They're __________ very fast. ( )
A.runing B.running C.to run D.runs
【答案】B
【解析】
句意:他们正跑得很快。由句子可知时态为现在进行时,结构是be doing,run的现在分词是running,故答案为B。