—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
网友回答
A. has joined
B. joins
C. had joined
(答案→)D. joined
解析：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。