（5）注意几组时态的区别：

　　◆ 一般过去时与现在完成时：

　　时间上有差异：凡有过去时间的均用过去时态，不能用完成时态，如含有ago、last year、just now、the other day等。

　　结果上有差异：现在完成时强调的是对"现在"的影响和结果，动作到现在刚完成或还在继续；一般过去时强调的是动作发生在"过去"，和现在毫无关系。

　　◆ 过去完成时与一般过去时：过去完成时强调的是"过去的过去"；如出现同一主语连续几个动作（"连谓"）形式则只用一般过去时即可。

当堂检测：

　　 (1) -- Are you a visitor here?

-- That's right. I______ round the world and now my dream of coming to China _______ true.

　　A. have traveled； has come

　　B. was traveling； had been come

　　C. am traveling； has come

　　D. have traveled； has been come

　　 (2) --_________Betty this morning?

　　 -- Not yet, but she is sure to be here before noon.

　　A. Have you seen B. Will you see

　　C. Do you see D. Did you see

(3) Jim talked for about half an hour yesterday. Never________ him talk so much.

　　A.I heard B. did I hear

C.I had heard D. had I heard

　　 (4) The children __________very quiet； I wonder what they _________up to.

　　A. were； are being B. are being； are

　　C. are； do D. are being； do

　　 (5) -- Look at the black clouds. It ___________ soon.

　　 -- Sure. If only we_________ out.

　　A. is raining； didn't come

　　B. is to rain； won't start

　　C. will rain； haven't started

　　D. is going to rain； hadn't come

(6) He_______articles for our wall-newspaper these three years, and he ______about forty articles.

　　A. has been writing； has written

　　B. has been writing； wrote

　　C. is writing； has been writing

　　D. has written； has written

　　 (7) She__________ to the office than she got down to writing the report.

　　A. has no sooner got B. had hardly got

　　C. no sooner got D. had no sooner got

(8) When he was alive, the old scientist used to say that knowledge______from practice and he gained his experience by doing a lot of practical work.