虫蜡在包糖衣时主要用于（）
A.打光
B.糖衣层
C.粉衣层
D.隔离层
E.有色糖衣层
参考答案：A
They are _____ in Shenzhen now, I think they must enjoy themselves.[ ]
A. on holiday
B. on duty
C. on business
D. on watch
设y=y(x)是由方程y2+xy+x2-x=0确定的满足y(1)=-1的连续函数，则
