问题
选择题
—Have you known Dr. Jackson for a long time?
—Yes, since she________ the Chinese Society.
A．has joined
B．joins
C．had joined
D．joined
答案
答案：D
该句完整的句式是：I have known Dr. Jackson since she joined the Chinese Society. since后跟的时间状语从句要用一般过去时，表示自从过去某个时间发生的动作到现在以来有多长时间了。