How soon通常在一般將來時(shí),意為"再等多長時(shí)間?","多長時(shí)間才……?"
是對(duì) "in +時(shí)間段"（ in ten minutes/two hours/ a week）提問.
Can you tell me how soon you can be ready?你能告訴我你多久能準(zhǔn)備好嗎?
how long與how soon都可以用來提問時(shí)間.
但是how long一般用于提問完成時(shí),例如：
How long have you been there?-I have been there for 3 years.
而how soon是用于提問將來時(shí)的,例如：
How soon will you arrive here?-I will arrive here in 3 hours.
換一個(gè)說法.如果答句中用的介詞是for前面就要用how long；如果是in,前面要用how soon
how long指的是多長時(shí)間,多長的長度
比如:how long have you been collecting
dolls 你收集玩具多長時(shí)間了?
how soon指的是多快,比如how soon will you be there?你多快能到那兒?