问题
选择题
We want to know he will come back, as we are worried about his safety.
A．how often
B．how soon
C．how much
D．how long
答案
答案：B
题目分析：how often多久一次；how soon多久；how much多少钱；how long多长。句意：我们想知道他还有多久回来，我们很担心他的安全。结合语境可知选B。