油井机械法堵水只适合单纯出水层，并且在出水层上下距油层有2.5m以上的稳定夹层。
参考答案：错
To keep fit, you should take more______ . Don’t be always busy doing your ______.
A．exercise; exercise
B．exercises; exercises
C．exercises; exercise
D．exercise; exercises
树脂自硬砂的配方是什么？
