测量上确定点之间的位置关系是通过测定三个定位元素来实现的,下面哪个不在其中( )。
Goods are carried by several of transport--on road or rail, by sea or air.
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
免费的网站请分享给朋友吧