【题目】—Do you consider worthwhile for them to have made that experiment?
— Of course. After all, it has paid off.

A. SufferingB. Being sufferedC. SufferedD. Having suffered

— There isn’t any Brown here. You _______ the wrong number.

A.can’t have dialedB.must have dialed

C.might dialD.could dial

【题目】I woke up with bad headache, yet by evening the pain had gone.
A. the; the
B. the; an
C. a; the
D. a; an

【题目】After completing and singing it. Please return the form to us in the envelope _____.
A.providing
B.provided
C.having provided
D.provide

【题目】The manager was concerned to hear that two of his trusted workers ______.
A.will leave
B.are leaving
C.have left
D.were leaving