when的用法当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?

副词 adv.什么时候,何时
at what time
· When can you come to see me?
你什么时候来看我?
· When did you go to bed last night?
昨晚你什么时候睡觉的?
· When are you going to return it?
你准备什么时候还（书）?
副词 adv.是…时候
at which;on which
· Please tell me when we'll have the meeting.
请告诉我我们什么时候开会.
· I wonder when that was.
我不知道那是什么时候的事.
副词 adv.在…的时候
at or during which
· How I regretted the days when I had played and should have studied!
我多么懊悔我本该好好学习却玩掉了的那么多的日子!
副词 adv.那时
but at that moment
· It happened on a day in November when the weather was very wet and cold.
这事发生在十一月的一天,那时天气又潮湿又寒冷.
· We were about to start,when it began to rain.
我们刚要出发时开始下雨了.
连词 conj.当…时
at the time when
· It happened when I was living in the country.
这事发生在我住在农村的时候.
· It was raining when we arrived.
我们到达时,天正下着雨.
· He always comes on those days when I am busy.
他总在我忙的日子来.
· I was walking along the stream,when I met my teacher of English.
当我沿着小溪散步时遇到了英语老师.
连词 conj.一…就
immediately after
· When I had finished dinner I went to bed.
我吃完饭就睡觉了.
· She was very surprised when she saw me.
她见到我非常惊讶.
· Let us set out when the sun has risen.
太阳一出来,我们就动身.
代词 pron.（关系代词）那时
which time
· I came here in 1949,since when I have been engaged in this work.
我1949年到这里,从那时起我就担任这项工作.
· We came a week ago,since when the weather has been bad.
我们在一星期前来此,从那时起天气就一直不好.
代词 pron.（疑问代词）什么时候
what time
· Since when have you been here?
你从何时起在此地?
· Until when can you stay?
你能呆到什么时候?

when
ad.
1. (用作疑问副词)什么时候,何时
I'd like to know when they'll let him out.
我想知道他们什么时候放他。
When did you last see Margaret?
你上一次见到玛格丽特是什么时候?
2. (用作关系副词,引导关系从句)当...时
There were...

when于何时；在那时；当……时；尽管
（1）when did you come
（2）It was raining when we arrived.
（3）How can I help them to understand when they won”t listen to me?
1.什么时候/场合When did you last see him?