2015年衛(wèi)生類職稱英語考試語法：時態(tài)

1)現在完成進行時態(tài) (have/has been + -ing 分詞構成): 動作或狀態(tài)從過去某時開始,繼續(xù)到現在,可能繼續(xù)下去,也可能剛剛結束.

I've been writing letters for an hour.

I've been sitting in the garden.

2)過去完成進行時(由had been + ing分詞構成): 過去某個時刻以前一直在進行的動作

I'd been working for some time when he called.

We had been waiting for her for two hours by the time she came.

3)將來完成進行時: 將來某個時刻以前一直在進行的動作.

By next summer, he will have been working here for twenty years.

In another month's time she'll have been studying here for three years.

4)將來完成時(由shall/will have + 過去分詞構成): 將來某時已發(fā)生的事.

I shall have finished this one before lunch.

They'll have hit the year's target by the end of October.