．People have planted a lot of trees and grass in order to ____ wind and sand in the desert．
| A．hold down | B．hold up | C．hold back | D．hold out |
--- Could you do me a favour?
--- It depends on ______ it is.
| A．which | B．whichever | C．what | D．whatever |
Doris' success lies in the fact _________ she is co-operative and eager to learn from others.
| A．which | B．that | C．when | D．Why |
These shoes look very good. I wonder __________.
| A．how much cost they are | B．how much do they cost |
| C．how much they cost | D．how much are they cost |
He spoke proudly of his part in the game, without mentioning ________ his teammates had done.
| A．what | B．which | C．why | D．while |
One advantage of playing the guitar is _________ it can give you a great deal of pleasure.
| A．how | B．why | C．that | D．when |