方法。鲍勃左手前右手后握住一柄已发动的链锯，对着一根竖立的木桩，将木桩顶上锯掉一小截，然后关掉发动机，对工人们讲解。
鲍勃：Using a saw is easy, but sometimes it could be tribsp;or dangerous. The most on act arises from the so-called \quot;kickback.\quot; (链锯使用简单，但有时也会有危险。最常见的事故是由所谓的后弹rdquo;引起的。)
亚当斯和两名学生来到铁丝围栏边上，站住，观看鲍勃的讲解。亚当斯手拿广告纸。
鲍勃用手指着锯头的顶部，继续：If a tooth at the upper quadrant cuts into wood but is not able to bsp;it through, the rsquo;t tinue moving. At this moment the bar may jump up toward you. This is kickbackrdquo; and could be