how long how often when whay time的用法

是what time 吧?! 呵呵~
how long,how often,how soon的区别
how long 有以下两个主要意思：
1. 表示多长时间,主要用来对一段时间(如three days, four weeks 等)提问.
如: A：How long did he stay here? 他在这儿呆了多久?
B：About two weeks. 大约两个星期.
A：How long does it take to get to London from here? 从这里到伦敦要多长时间?
B：At least ten hours. 至少要10个小时.
2. 表示某东西有多长.
如： A：How long is the river? 这条河有多长?
B：About 500 km. 大约500千米.
how often指每隔多久,主要用来对频度副词或状语(如：once a week, three times a month 等)提问.
如： A：How often does he come here? 他(每隔)多久来一次?
B：Once a month. 每月一次.
A：How often do you visit your mother? 你多长时间看你妈妈一次?
B：Once a week. 一周一次.
how soon指再过多久,主要用来对表示将来的一段时间(如：in an hour, in two weeks 等)提问.
如：A：How soon will he be back? 他要多久才回来?
B：In an hour. 1 小时以后.
A：How soon shall we know the results? 我们多久能知道结果?
B：I don’t know. 我不知道.

what time常用来问钟点,而when除了问钟点外,还可用来问日期,月份,年份等.有时两者可以换用,有的场合不可以.
1.问钟点时,可以换用.
When do you go to school?
What time do you go to school?
2.问日期,月份,年份等,只能用when
When were you born? I was born on July 2,1972.
3,当问某事在某天的什么具体时间进行,只能用what time
What time did you call this afternoon?
I called at 4:00 this afternoon.
另注: when :一,副词 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.
When did you last see Margaret?
2.(用作关系副词,引导关系从句)当...时
There were times when I didn't know what to do.
二,连接词 conj.
1.当...时
John got engaged to her when travelling last winter.
Don't get excited when you talk.
2.既然,考虑到
How can he get the promotion when his boss dislikes him?
3.虽然,然而
I had only fifteen dollars on me when the book I wanted cost twenty.
4.在那时,然后
三,代词 pron.
1.什么时候,那时
Since when has she taught here?
四,名词 n.
1.(事件发生的)时间[the S]
what time:什么时间 问具体时间,如几点钟
例: What time is it now?
What time is suitable for us to meet?