I know Mr. Brown; we ______ to each other at an international conference.

    A. are introduced             B. are been introduced

    C. were introduced           D. had been introduced

 I know Mr Brown; we      to each other at an international conference.

    A. are introduced               B. have been introduced

    C. were introduced            D. had been introduced

I know Mr. Brown; we ______ to each other at an international conference.

1. A.
   are introduced
2. B.
   are been introduced
3. C.
   were introduced
4. D.
   had been introduced

I know Mr. Brown; we ________ to each other at an international conference.

[　　]

A．are introduced

B．have been introduced

C．were introduced

D．had been introduced