when的用法

Question

当when表示什么时后面一般将来时改一般现在时？
什么时候不改？

最好能举例，不要一大段过来，谢谢了！

Answer 1

具体你可以参考这一段。
when，while，as引导时间状语从句的区别
when，while，as显然都可以引导时间状语从句，但用法区别非常大。
一、when可以和延续性动词连用，也可以和短暂性动词连用；而while和as只能和延续性动词连用。
① Why do you want a new job when youve got such a good one already？（get为短暂性动词）你已经找到如此好的工作，为何还想再找新的？
②Sorry，I was out when you called me．（call为短暂性动词）对不起，你打电话时我刚好外出了。
③Strike while the iron is hot．（is为延续性动词，表示一种持续的状态）趁热打铁。
④ The students took notes as they listened．（listen为延续性动词）学生们边听课边做笔记。
二、when从句的谓语动词可以在主句谓语动作之前、之后或同时发生；while和as从句的谓语动作必须是和主句谓语动作同时发生。
1．从句动作在主句动作前发生，只用 when。
①When he had finished his homework，he took a short rest．（finished先发生）当他完成作业后，他休息了一会儿。
②When I got to the airport，the guests had left．（got to后发生）当我赶到飞机场时，客人们已经离开了。
2．从句动作和主句动作同时发生，且从句动作为延续性动词时，when，while，as都可使用。
①When ／While ／As we were dancing，a stranger came in．（dance为延续性动词）当我们跳舞时，一位陌生人走了进来。
②When ／While ／As she was making a phonecall，I was writing a letter．（make为延续性动词）当她在打电话时，我正在写信。
3．当主句、从句动作同时进行，从句动作的时间概念淡化，而主要表示主句动作发生的背景或条件时，只能用 as。这时，as常表示“随着……”；“一边……，一边……”之意。
① As the time went on，the weather got worse．（as表示“随着……”之意）
② The atmosphere gets thinner and thinner as the height increases．随着高度的增加，大气越来越稀薄。
③As years go by，China is getting stronger and richer．随着时间一年一年过去，中国变得越来越富强了。
④The little girls sang as they went．小姑娘们一边走，一边唱。
⑤The sad mother sat on the roadside，shouting as she was crying．伤心的妈妈坐在路边，边哭边叫。
4．在将来时从句中，常用when，且从句须用一般时代替将来时。
①You shall borrow the book when I have finished reading it．在我读完这本书后，你可以借阅。
②When the manager comes here for a visit next week，Ill talk with him about this．下周，经理来这参观时，我会和他谈谈此事。
三、when用于表示“一……就……”的句型中（指过去的事情）。
sb．had hardly（＝scarcely） done sth．when．．．＝Hardly ／ Scarcely had sb．done sth．when．．．
①I had hardly ／scarcely closed my eyes when someone knocked at the door．＝Hardly ／ Scarcely had I closed my eyes when someone knocked at the door．我刚一闭上眼，就有人在敲门了。
②I had hardly ／scarcely entered my room when the telephone rang．＝Hardly ／Scarcely had I entered my room when the telephone rang．我刚一走进房门，电话就响了。

Answer 2

1
When
I
have
money
in
the
future,
i'll
buy
a
new
bike
for
you.(
when
引导了时间状语从句，从句用一般现在时，主句用将来时）
2，When
i
came
in
,I
found
no
one
left
(
when
引导了时间状语从句,表示过去的事实，主从句都用过去时）
3.I
was
reading
a
book
in
the
room
when
a
dog
ran
in.(when=and
at
that
time)
=While
i
was
reading
a
book
in
the
room
,
a
dog
ran
in
4
Hardly
had
he
arrived
when
he
began
to
work.(
hardly.had
+主语+过去分词。。when
+主语+谓语。）

Answer 3

当when表示什么时后面一般将来时改一般现在时？
我是个英语老师
简单说来,用在表将来的条件和时间状语从句中,一般将来时改一般现在时
When we meet again, i am sure you will be more beautiful.
If you give me some more time, i will do it better.

Answer 4

1. When did that happen?
那件事是什么时候发生的？

2. Turn off the switch when anything goes wrong with the machine.
如果机器出故障，就把开关关掉。

3. He was fond of drawing when he was a child.
他还是个孩子时就喜欢画画。

4. It was raining when we arrived.
我们到的时候正在下雨。

5. It was the sort of morning when everything goes wrong.
那天上午就是那样，事事不顺心。

6. How can they learn anything when they spend all their spare time watching television?
他们把所有的空闲时间都用来看电视了，还能学什麽东西呢？

7. The Queen's last visit was in May, when she opened the new hospital.
女王上次来访是在五月份，她那时主持了这座医院的落成典礼。

Answer 5