单项选择题
The sun heats the earth,（）makes it possible for plants to grow.
A．that B．where C．which D．what
单项选择题 Students buying a car should take into account（）
单项选择题 Just as people differ in their ability to hear sound, （） differ in their appreciation of sounds.
单项选择题 Seldom（）any mistake during his past ten years of service there.
