Question

--- ____ have you been a member of Greener China?
--- For two years.

A．How often

B．How long

C．When

D．How far

Answer 1

B

试题分析：How often多久一次；How long多长，多久；When什么时候；How far多远；根据下文，两年了。可知上文指的是，你成为绿色中国的一员多久了？故选Ｂ。