—I'msorrytokeepyouwaiting.—Oh,notatall.Ihereforonlyafewminutes.
—I'msorrytokeepyouwaiting.
—Oh,notatall.Ihereforonlyafewminutes.
[]
A.was
B.is
C.havebeen
D.hadbeen
答案选的是C,但是我没想通,每个选项都要做一下解释.