主语+be动词(am, is, are)+动词ing.
It is raining now. My parents are reading newspapers in the sitting room. Look! The children are having a running race now.
经常反复发生的事情或动作，常与often, usually, sometimes, always, every day(week year…) on Sundays等词连用。
主语+动词原形；当主语为第三人称单数即he,she, it, Tom, my mother, the boy等词时，动词后加s或es.
We have an English lesson every day. Do the boys run faster than the girls? Yes, they do.
问句借助于do, does否定句借助于don’t, doesn’t，后面动词一定要还原。
发生在过去的事情或存在的状态，常与just now; a moment ago; … ago; yesterday; last ( week; month; year; Monday; weekend); this morning等词连用。