5道简单英语单选题,16.The dean of the Philosophy Department requested

5道简单英语单选题,
16.The dean of the Philosophy Department requested that the visiting scholar ____ a lecture on the philosopher Sartre.
A.gave
B.give
C.would give
D.had given
17.When Edison invented the light bulb,he tried over 2000 experiments ____ he got it to work.
A.as
B.after
C.when
D.before
18.The young lady coming over to us____ our English teacher; the way she walks tells us that!
A.must be
B.can be
C.would be
D.could be
19.They have learned about____in recent years.
A.several hundreds English words
B.hundreds of English words
C.hundred of English words
D.several hundred English word
20.I was disappointed with the film.I had expected ____ to be much better.
A.that
B.this
C.one
D.it