问题补充:
the prices and functions of different types of computers before you make up your mind which to buy.
A. To compare
B. Comparing
C. Compared
D. Compare
答案:
A. To compare
B. Comparing
C. Compared
(答案→)D. Compare
解析:考查祈使句。句意:在你下定决心要买某台电脑之前,你要比较一下不同的电脑的价格和功能。祈使句表示的一种语气,使用时,要把动词原形放在句首。故D正确。