2. 现在进行时(be doing) 用法:现在正在进行的动作。 3. 现在完成时(have done) 用法: A) 表示动作到现在为止已经完成或刚刚完成。 例:I bought a new house, but I ___ my old one yet, so at the moment I have two houses. A) didn't sell B) sold C) haven't sold...