在英语中，"useful"是形容词，意思是有用的、有益的、有价值的。

这个词的来源可以追溯到拉丁语 "uti"，意思是"有用的"或"有益的"。

以下是一些例句：

This dictionary is very useful for learning new words.
(这本词典对于学习新单词非常有用。)

His advice was really useful, and it helped me solve the problem.
(他的建议非常有用，帮助我解决了问题。)

These tips are useful for anyone trying to improve their pubpc speaking skills.
(这些提示对于任何想要提高公共演讲技巧的人都很有用。)

This tool is very useful for fixing small engines.
(这个工具对于修理小型发动机非常有用。)