用所给的单词的正确形式填空 1.Look!The boys( )[swim]in the river.doing?

1.Look!The boys (are swimming) in the river.
因为从“look"可以看出,这里是现在进行时,又因为”boys(男孩)"是复数,因此要用“be swimming"的”be"要用“are".
翻译：看!男孩们正在河里游泳.
补充：be包括(is,am,are,was,were)
其中,were为are的过去式,was为(am,is)的过去式.