_______ caused the accident is still a complete mystery.
A．What B．That C．How D．Where
Whitney Houston’s sudden death suggests that drug abuse is such a serious problem ___we should deal with properly.
A．as B．that C．which D．where
---The “No.1 Document” is designed to help the rural population increase their incomes.
---I believe that peasants’ life _____ better and better.
A．will have got B．has got C．gets D．will be getting
It was not until the end of last year _____ the economy in our country began to develop rapidly.
A．when B．that C．which D．in which
---Anna, you look so tired and wet all over!
---Well, you know, all morning I _______ my books to my new office on the third floor.
A．am moving B．have moved C．had moved D．have been moving
---It was dangerous to throw that bottle out of the window. You could have hurt someone.
---I’m so sorry! I _______ .
A．am not thinking B．wasn’t thinking C．haven’t thought D．don’t think
