目前，常用的清管器根据其组成的不同可分为机械清管器和（）两类。
A.钢制清管器
B.钢砂清管器
C.旋转清管器
D.泡沫塑料清管器
参考答案：D
很多FTP服务器都提供匿名FTP服务。如果没有特殊说明，匿名FTP账号为
A．anonymous
B．guest
C．niming
D．匿名
The traffic police stopped three trucks heavily loading with merchandise that looked as grain bags.
A．that were loading ... like
B．loaded with ... like
C．to load with ... for
D．loaded with ... for
