1. During construction, builders were threatened with $7,500 fines for felling trees unnecessarily. 施工期间，建筑商如果不必要地砍伐树木可能面临7500美元罚款。
2. These beavers do know how to build dams, and do so if the need arises, as may occur if they are forced to relocate after felling and consuming all nearby trees. 这些海狸知道如何建造水坝，而且在有需要的时候就会这么做，比如当它们在砍伐和消耗了附近所有的树木后被迫迁移的时候。
3. He gashed his leg while felling trees. 他砍树的时候割破了腿。
4. Felling unwell and being generally weak we want people to be healthy even when they are old. 即使老了通常会变得体弱多病，我们也希望人们能保持健康。
