手机的通讯功能、冰箱的保鲜功能属于产品的（）。
A.核心层
B.形式层
C.附加层
D.期望层
参考答案：A
He worked hard before the college entrance examination, and it _______. His dream to go to college came true.[ ]
A. showed off
B. paid off
C. put off
D. took off
什么要对钢带进行矫平？
