David has __much work to do that he is staying late at his office.
A. such
B. So
C. very
D. enough
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I didn't answer the phone__I didn't hear it ring.
A. if
B. unless
C. although
D. Because.
Busy_he was, he tried his best to help us. "
A. as
B. when
C. since
D. for
After the war, a new school building was put up__there had once been a theatre.
A. as
B. where
C. if
D. when
Don't be discouraged__you have fallen behind others.
A. whether
B. as if
C. even if
D. however