The professor gave us _____ talk on multicultural Canadian society, _____ topic few of us are familiar with.

A．a; the

B．the; a

C．a; a

D．the; the

易制毒化学品出口许可证实行（）。

A.“一批一证”制

B.“一证一关”制

C.“一证二批”制

D.“分批一证”制