Parliament didn't think the Prime Minister did enough in the improvement of fair employment,
问题描述：
Parliament didn't think the Prime Minister did enough in the improvement of fair employment,
________ he was asked to write to Parliament for further explanation.
A.therefore
B.so
C.since
D.as
此题选哪个答案,为什么?
答
选B,因为therefore是个副词,后面不能连接分句,and therefore=so.