it is/has been+时间段+since since后面接完成时还是一般过去?求例子详解!拜谢~
问题描述：
it is/has been+时间段+since since后面接完成时还是一般过去?
求例子详解!拜谢~
答
用一般过去时例如：It has been a while since the last time I saw you.有好一阵子没见你了.It has been a few decades since the computer came into being.自从计算机问世以来已经有几十年的时间了.It is years s...