天然土经开挖后,其体积因松散而增加,虽经振动夯实,仍不能完全恢复到原来的体积,这种性质称为土的( )。
A.渗透性
B.干密度
C.密实度
D.可松性
参考答案:D
How many times have you found yourself arriving at school to start your day, only ________ that you left your homework at home?
A.having discovered
B.discovering
C.to discover
D.Discover
我国的劳动年龄是指( )岁。
A.15
B.16
C.17
D.18