这些动词均含有“有益于，有益”之意。
avail ：较文雅，常见于历史小说、演说或讲道中，较少用于日常话语，侧重功效或效力。
- His efforts were to no avail
他徒劳无功。 - I apologized repeatedly, but to little avail.
我一再道歉，但丝毫没有奏效。 - I avail myself of this opportunity to renew to you the assurances of my highest consideration.
顺致最崇高的敬意。 - Of what avail is it?
何济于事？ - Now it's done, regrets are of no avail.; It's no use crying over spilt milk.
事已如此，后悔也是枉然。
benefit ：通常既可指个人情况（如身体、智力或精神状态等）的好转或改善，又可指对实现某个目标等带来的好处。
- We should spend the money on something that will benefit everyone.
我们应该把这笔钱花在大家都能得益的事上。 - Both sides have benefited from the talks.
双方都从谈判中获益。
profit ：着重于物质方面的受益，常用于财富或知识等方面的得益。
- Farmers are profiting from the new legislation.
新法规使农民受益。 - We tried to profit by our mistakes (= learn from them).
我们努力从错误中吸取教训。 - Many local people believe the development will profit them.
当地的许多人认为，这项开发将对他们有利。
