国家按用途把土地分为( )。
A．自留地
B．宅基地
C．农用地
D．未利用地
E．建设用地
参考答案：C,D,E
The boy was so careless that the glass fell from his hand and it _____ on the floor.[ ]
A. broke in
B. broke down
C. broke up
D. broke out
对于下行上给全循环式管网，为了防止配水管网中分离出的气体被带回循环管，那么应当把每根立管的循环管始端全部都接到其相应热水配水立管最高点以下（）处。
A.0.15m
B.5m
C.1m
D.0.5m
