how long有以下两个主要意思:
1、表示多长时间,对一段时间进行提问。
-Howlong have you learned English?
-你学英语多久了?
-For 3 years ./Since 3 years ago./Since I came to this school.
-三年了。/从三年前开始。/从我来到这所学校。
2、表示某东西有多长。
-How long is the river?
-这条河有多长?
-About 500 km.
-大约500千米。(大约)
-It’s 500 km.(确定)
How long does it take to get to London from here?
从这里到伦敦要多长时间?
How long is the tunnel?
隧道有多长?
You sneak a look at your watch to see how long you've got to wait.
你偷偷地望一眼手表,看看要等多长时间。