how long 和how soon的区别.

how long与how soon都可以用来提问时间.
但是how long一般用于提问完成时,例如：
How long have you been there?-I have been there for 3 years.
而how soon是用于提问将来时的,例如：
How soon will you arrive here?-I will arrive here in 3 hours.
换一个说法.如果答句中用的介词是for或about 前面就要用how long；如果是in,前面要用how soon 所以你这道题应该用how long.
how long指的是多长时间,多长的长度
比如:how long have you been collecting
dolls 你收集玩具多长时间了?
how soon指的是多快,比如how soon will you be there?你多快能到那儿?
下面是一些例子：
How soon
How soon will you be through?:
您要用多长时间打完电话?
How soon can you be ready?:
你最快要多长时间才能准备好?
How soon can we expect delivery?:
我们多久能收到邮件?
How long
例句与用法:
1.How long have you been here?
你在这里多久了?
2.How long will it take to get to your house?
到你家要多久?
3.How long did it last?
持续了多久?
4.How long will it take me to get there?
到那儿要多长时间?
5.How long will the discharge of the cargo take?
卸货需要多久?
6.How long can you stare without blinking your eyes?
你能瞪着看多长时间不眨眼?
7.How long has she been pregnant?
她怀孕多久了?
8.I can't recall how long it has been.
我回忆不起来多长时间了.

第一个是问时间的长短，第二个是频率，次数的多少

how soon是用于将来时态，意思为什么时候。但具体也看语境。
比如：how soon will you come back?
how long的时态一般用于过去时，也看语境吧。
e.g.How long have you been here?
注意，how long是一个时间段而不是时间点。
How often很容易解释啦。它是一个对频率提出问题的疑问...