常见的有以下一种情况:
在宾语从句中，当主句的时态为现在的某种时态(一般现在时、现在进行时、现
主过从过在完成时等)后面从句时态不受主句限制，可选用各种适合的时态。
例如:
Do you know when we'll have a football match?你知道我们什么时候举行足球赛
吗,
You know he has gone to Shanghai.你知道他已去上海了。
【特别关注】
1.当宾语从句表述的是客观事实、科学真理、现在的习惯动作以及格言等时，只
能用一般现在时。例如:
The teacher told us that light travels faster than sound.老师告诉我们光速比音速要
快。
2.如果主、从句表示的动作是一前一后发生的，则先前的用过去完成，在后的只
能用一般过去时态。
When he got there, the train 
had left. 当他到那儿的时候，火车已经开了。 主过从过
【小试身手】
1. If he ___ harder , he will catch up with us soon. (04 北京)A. study B. studies C. will study D. studied 2. I will go swimming
with you if I ___ free tomorrow.
(04哈尔滨)A. will be B. shall be C. am D. was 3.If you ___ a chance to study in a foreign country ,just take it .
(04 苏州)A. getting B. had got C. will get D. get 4. Don’t leave until he ___ back.()
A. have come B. comes C. will come D. came 5. “ Shall we have the volleyball match tomorrow?” “ Oh, it will be put off if it ____.
(04 黄冈)
