ruler的复数形式怎么写

　　例句：

　　His guitar makes a noise like a wooden ruler being twanged upon a desk

　　他的吉他发出一声仿佛木尺弹在课桌上的噪音。

　　He cracked me on the head with a ruler.

　　他用尺子猛击我的头部。

　　The ruler cracked and splintered into pieces

　　尺子裂开了，碎成了小片。