现在进行时
表示正在发生的事情或进行的动作，常与now,listen,look等词连用，结构是主语+be动词(am, is, are)+动词ing.
如：It is raining now.
外面正在下雨
It is six o’clock now.
现在6点了
My parents are reading newspapers in the sitting room.
我父母正在客厅看报纸
Look! The children are having a running race now.
看！孩子们正在赛跑
问句将be动词移前，否定句在be动词后+not.
