同学你好，该知识点来自沪江网校《雅思语法精讲【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
1.“My neighbor who went to Tokyo for a holiday, which he couldn't return home, because he didn't have enough money.” 这个句子是不对的。存在以下问题：
句子结构混乱。“who went to Tokyo for a holiday” 是一个定语从句，用来修饰 “My neighbor”，但后面的 “which he couldn't return home” 使用不当，这里不应该用 which 引导的定语从句来表达 “他无法回家” 这个意思，并且和前面的句子逻辑不连贯。
正确的表达可以是 “My neighbor who went to Tokyo for a holiday couldn't return home because he didn't have enough money.”
2.“He walked quietly down the corridor so that he didn't want anyone to hear him.” 这个句子从语法角度来说逻辑有些奇怪，通常 “so that” 引导目的状语从句时，表达的是 “为了……”，而原句这样表达会让人觉得 “他不想让别人听到他” 是他安静走路的结果，而不是目的。更合适的表达应该是 “He walked quietly down the corridor so that no one would hear him.”
或者按同学的想法，可以改成He walked quietly down the corridor because he didn't want anyone to hear him.
关于能否省略 so that 后面的主语 “he”，在这个句子中，如果省略会导致句子意思不明确，所以不能省略。因为省略后就变成了 “He walked quietly down the corridor so that didn't want anyone to hear him.”，“didn't want” 没有了主语，不知道是谁不想让别人听到
3.“They cleared the ground to build a house.” 这个句子是对的，“to build a house” 是动词不定式作目的状语，表明他们清理地面的目的是建房子。
“They cleared the ground to they want to build a house.” 这个句子是不对的，“to” 后面不能直接接 “they want to” 这样的结构。这里的 “to” 是不定式符号，后面应该接动词原形，不能接句子。原句中的 “to build a house” 已经正确地表达了目的，不需要也不能再添加 “they want to” 这样的内容，不存在省略的说法。
希望对同学油帮助~