不适于在过硬或过软的土中打桩的是下列的( )。
A．振动桩锤
B．单动汽锤
C．柴油桩锤
D．双动汽锤
参考答案：C
There was a time_____we went to the country and stayed with the farmers there.
A．which
B．that
C．when
D．while
下列关于水泥中碱含量的计算正确的是( )。
A．Na2O+0.658K2O B．Na2O+0.856K2OC．K2O+0.658Na2O D．K2O+0.856Na2O
