When he was alive, the old scientist use
问题:
When he was alive, the old scientist used to say that knowledge __from practice and he gained his experience by doing a lot of practical work.
A.was coming
B.had come
C.comes
D.would come
When he was alive, the old scientist used to say that knowledge __from practice and he gained his experience by doing a lot of practical work.
A.was coming
B.had come
C.comes
D.would come