Question

I'm sorry to have kept you waiting A.Don't mention it B.No problem

Answer 1

c
试题分析：考查交际用语：a.
don’t
mention
it!不用谢，b.
how
come?怎么回事？c.
that’s
all
right.没关系，d.
so
what?那又怎样？句意：很抱歉给你带来这么多的麻烦。--没关系，选c。