machine head的用法和样例：
例句
- There is a bolster across the head of the bed.
床头上有一个长枕垫。 - The general was lying on the bed, his back against the headboard, hands clasped behind his head.
将军躺在床上，背靠床头板，头枕在交叠的双手上。 - Spindle feeds and speeds are controlled by selector levers which engage the proper gears in the drill head.
主轴的进能量和转速是通过选速杆使主轴箱中的适当齿轮相啮合而控制的。
