–You are Mr. Zhang, aren’t you? --______. 

．We’ve published large quantities of books. This year______ we’ve published three million copies.

A car engine cannot run smoothly without motor oil.____ our body cannot function efficiently without vitamins.

I lost my wallet last week, but ____ it didn’t contain much money at that time.

David apologized to me yesterday. __, I won't forgive him for it was not the first time that he had hurt me.