【简答题】We plant trees in spring every year.
【单选题】在地形图上确定某点的高程的依据是 ( ) 。
【单选题】To avoid the mistakes of our forefathers, the author suggests that ______.
C.
natural sciences be taught to everybody
D.
environmental education be directed to everyone
【单选题】We must plant more trees, The more trees we plant ,___pollution we’ll have.
【简答题】轨道交通通信系统包括电话通信子系统、专用通信子系统、( )、( )和数据通信子系统。