现在进行时——表示现在正在进行的动作构成：主语＋be动词＋动词的现在分词＋其它成分 再答： We are having lunch. He is reading a book. The dog is running after a cat. The boys are swimming across the river.
再答： 变疑问句将be动词移到句首 Are we having lunch? Is he reading a book? Is the dog running after a cat? Are the boys swimming across the river?
再答： 更多资料请见：http://www.vickeynce.com/club/discuss/?id=10
