在井内液体干净、落物不被掩盖时,也可用()连接磁力打捞器下人井底,反复将打捞器自井底上提0.5~lm,几次即可捞出井下铁质落物。
A.钢丝绳
B.油管
C.钻杆
D.套管
参考答案:A
After the long march, the troops reached their destination, ____________.
A.hungry and friendly
B.hungry and tired
C.hungrily and tiredly
D.hungrily and tired
右图中,起折射作用的结构主要是
A.①晶状体
B.②角膜
C.③虹膜
D.④视网膜