A:物种多样性原理
B:系统整体性原理
C:协调与平衡原理
D:系统学与工程学原理
我会填上适当的量词。
一____席梦思床 一____火车票 一____金发姑娘 一____矿泉水
以A(1,3)和B(-5,1)为端点的线段AB的垂直平分线方程是( )
Neither Jam nor his parents _______ places of interest here since they came to China.
—Shall we have a smoke here?
—No, we _____ because this is gas station and the worker is carrying some petrol.