（ ） I think I‘ll wait until the mail _______.
A. should come
B. is coming
C. comes
D. will come
（ ） We found ________.
A. the work hard for doing
B. hard to do the work
C. it hard for doing the work
D. the work hard to do
（ ） Professor Bixby warned his students ________ late for the examination.
A. not be
B. to be not
C. not to be
D. be not
（ ） I don‘t know what I’d have done if I _______ to make that decision.
A. would have
B. had had
C. have had
D. did have
