The girl usually does her homework _____ it is very late at night.
A:until
B:when
C:before
D:after
就为了省一点点钱而买最便宜的电脑是不明智的。
It ____ ____ ____ to buy the cheapest computer just to save a little money.
小宇实验时选用橡皮泥作为实验的材料,你认为选用这种材料对他的实验操作有什么好处? ____ 。