A ruler is a very useful tool. 尺子是非常有用的工具。

　　It can measure the length of an object. 它可以测量物体的长度。

　　There are many different kinds of rulers. 尺子有很多种。

　　Rulers are made of plastic, stainless steel, cloth and so on. 尺子是由塑料、不锈钢、布料等制成的。

　　We use a plastic ruler in the classroom. 我们在教室里使用塑料尺子。

　　A stainless steel ruler is usually used in a factory. 不锈钢尺子一般在工厂使用。

　　Why would you use a cloth ruler? 为什么会用到布尺呢？

　　They are used because cloth rulers can be bent easily. 使用布尺是因为它容易弯曲。