你没有必要介绍你的朋友库克。
在了解本文介绍的原理时，没有必要下载和安装以下组件，但这样做会使您掌握更多的知识。
It is not necessary to download and install the following components to understand the principles outlined in this article, but you will certainly be more knowledgeable if you do.
他花了很长时间介绍这本书，其实没有必要，因为学生们对它已经很熟悉了。
He unnecessarily spent a lot of time introducing this book, which the students are familiar with.
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