灰口铸铁常用来做机器设备的壳体和底座,是因为灰口铸铁的()性好。
A、减振
B、硬度大
C、弹性好
参考答案:A
下列属于生物因素对生物影响的是( )
A.春来江水绿如蓝
B.种豆南山下,草盛豆苗稀
C.雨露滋润禾苗壮
D.人间四月芳菲尽,山寺桃花始盛开
When you call on a Frenchman, you may chat for an hour or so, not even a coffee or water is offered.[ ]
A.during that time
B.by that time
C.during which time
D.by which time