It's been 2 years ____ I went to London and I've been used to living thereA before B since C after D when请讲解
问题描述：
It's been 2 years ____ I went to London and I've been used to living there
A before B since C after D when
请讲解
答
选B
答
b
这是一个句子结构It's been +一段时间+since 过去时的句子