问题
选择题
I don’t have to introduce him to you ________ you know the boy..
A．until
B．unless
C．since
D．but
答案
答案：C
当从句中有since+一般过去时，主句用现在完成时，故选C
搜题请搜索小程序“爱下问搜题”
I don’t have to introduce him to you ________ you know the boy..
A．until
B．unless
C．since
D．but
答案：C
当从句中有since+一般过去时，主句用现在完成时，故选C