Learner's definition of WHEN
1
: at what time什么时候 -
When will you return?你什么时候回来？
-
When did the American Civil War begin?美国南北战争是什么时候开始的？
-
The detective asked me when I last saw her.警探问我最后一次看见她是什么时候。
-
When is the next performance?下一场演出是什么时候？
-
(Do you) remember when that happened?（你）还记得那是什么时候发生的吗？
2
a : at, in, or during which在那时；在…期间 b : at or during which time在…时候；就在那个时候 3
informal : at a former and usually less successful time昔日，从前（通常指未发迹时） 2 when /ˈwɛn/ conjunction
2 when
/ˈwɛn/
conjunction
Learner's definition of WHEN
1
a : at or during the time that当…时 -
We went fishing when [=while] we were on vacation.我们度假时去钓鱼了。
-
I'll leave when you do. [=I'll leave at the same time as you]当你离开时，我也会离开。
-
When he finally showed up, he was drunk.当他最终露面时，他已喝得醉醺醺的。
-
When I was in school, we didn't have computers.我上学的时候，我们还没有电脑。
b : just after the time that在…之后（就）；一…就… -
You can go when the bell rings.铃一响，你就可以走了。
-
Call me when you get home.你一到家就给我打电话。
-
Things were better when he got a job.他找到工作后，情况就好转了。
c : at any or every time that每当…时 -
I cry when [=whenever] I hear that song.我一听到那首歌就会哭。
-
When he watches television, he falls asleep.他一看电视就会睡着。
2
a —
used to say what happens, is true, or can be done in a particular situation要是；如果 -
When you have no family, you are really on your own.如果没有家人的支持，你确实就得靠自己了。
-
We take the bus to school when it rains.如果下雨，我们就乘公共汽车上学。
-
A contestant is disqualified when she disobeys the rules.如果她违反规则，她的竞争者资格就会被取消。
-
When and if he comes, you can ask him. = If and when he comes, you can ask him.如果他过来，你可以问他。
b —
used to ask why or how something is done in the situation that exists既然 -
Why buy a newspaper when you can read the news online for free?既然你能在网上免费读新闻，为什么还要买报纸呢？
-
How can he buy the house when he has no money? [=he has no money, so how can he buy the house?]既然没钱，他怎么能买得起房子呢？
3
: in spite of the fact that : although尽管 4
: the time or occasion at or in which是…的时刻 3 when /ˈwɛn/ pronoun
Learner's definition of WHEN
: what or which time那时；什么时候 -
He retired in 1998, since when he has been devoting his time to gardening.自从1998年退休以后，他就把时间用来干园艺活。
-
You need the report by when?你什么时候要那份报告？