顾名思义，定语从句就是充当定语，用来修饰名词或代词的句子。被修饰的名词或代词称作先行同，在先行同和定语从句之间通常会有关系代词或关系副词，也即定语从句的引导词。常见的关系代词有that, which, who, whom, whose，关系副词有why, when,where。相比其他引导词引起的从句，由that, which, who和why引导的定语从句在雅思写作中使用的频率较高。
　　由who引导的定语从句 　　who引导的定语从句可以在句子中修饰表示人的名词或代词。此外，如果who在定语从句中充当主语，则它不能省略。
　　It offers many conveniences to the people who live there. 　　它给居住在那里的人们提供了很多便利。
　　Compared with those who are introverted, with little words and easy to be comedepressed, I prefer to make friends with people who would like to share happiness and sorrow with me. 　　相比那些内向、少言寡语且容易变得消沉的人，我更喜欢和愿意与我分享快乐和悲伤的人交朋友。 　　They are backed up by technicians who design instruments to collect data from athletes. 　　他们背后有技师的支持，这些技师设计工具以从运动员那里收集数据。
　　由why引导的定语从句 　　why引导的定语从句常用来修饰先行词reason，why在定语从句中充当原因状语。 　
　One reason why I support the building of a modern gym is that physical education class is very important to the well一being of students. 　　我支持兴建一座现代化体育馆的理由是，体育课学生们的健康非常重要。
　　The main reason why I choose the pig is that, in my opinion, the country's most valued animal does not need to be graceful or cuddly, but rather beneficial to the average person. 　　对我而言，我选择猪的主要理由是，我国有价值的动物不需要很优雅或者很可爱，而应该是对每个人都有用处。
　　The reason why I chose the forests as the most important is because they help us in so many ways. By saving the forests, I believe we can also save the planet. 　　我认为森林为重要，因为森林在很多方面都对我们有益。通过拯救森林，我相信我们也能够拯救地球。

　　以上是由广州启德教育小编为您整理的关于who丨why的定语从句的全部内容。