It is difficult for us to imagine_____ life was like for slaves in the ancient world.
_______ caused the accident is still a complete mystery.
Whitney Houston’s sudden death suggests that drug abuse is such a serious problem ___we should deal with properly.
---The “No.1 Document” is designed to help the rural population increase their incomes. ---I believe that peasants’ life _____ better and better.
It was not until the end of last year _____ the economy in our country began to develop rapidly.
---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.