饮料用水首先必须符合()。
参考答案:生活饮用水水质标准(GB5749-1985)
Arriving home,the boy told his parents about all the________which occurred in his dormitory.
A.occasions
B.incidents
C.matters
D.accidents
求点P(1,1,1)到旋转抛物面S:z=x2+y2在点(1,1,2)处的切平面的距离.