4.关系代词的格应与它在从句中充当的成分一致。特别要注意插入语，
　　如：Peter is the one who everybody believes will fail to bring off the contract. Peter 是那个人人都认为不能完成合同的人。(everybody believes 是插入语)
　　At the election I voted for the man whom I believed to be the most suitable.
　　在选举的时候我投了我认为最合适的那个人的票。
　　5.关系代词作从句的主语时，从句的动词必须和先行词的人称和数一致：
　　例：These are the operating instructions that/which are written in English 。
　　这就是用英文写成的使用说明。
　　Are you staying at the white house which/that is newly completed and which /that has 15 bedrooms, 3 kitchens and 4 toilets?
　　你是住在那幢刚刚竣工、有15个卧室、3个病房和4个卫生间的白色房子里吗?
　　So far as I know, there are many VIPs who are going to attend the reception.
　　就我所知有很多达官贵人将出席这个招待会。
　　6.非限定性定语从句不用that，只用who(whose, whom)和which代表人和物;
　　例：Her brothers, both of whom work in America, ring her up every week。
　　她的兄弟们??两个人都在美国工作??每个星期都给她打电话。
　　The buses, most of which were already full, were surrounded by an angry crowd，
　　那些公共汽车??大多已经坐满了人??被一群愤怒的人围着。
　　That tower block, which cost five million dollars to build, has been empty for five years.
　　那个塔楼空着已经5年了。建它花了500万美元。
　　Cricket, which I know very little about, is a very popular sport in England。
　　板球是英格兰非常流行的体育活动，我对它知之甚少。
　　The accounts of the company ,which I’ve been paying great attention to, are in balance.
　　公司的账目是保持平衡的。我一直非常注意这些账目。
　　7.关系副词(=介词+关系代词)：

关系副词	先行词	在从句中的作用	说明
when(=at / on / in / during which)	时间名词	时间状语	非正式文体中，有时用that代替关系副词
where(=in / at which)	地点名词	地点状语
why=(for which)	只有reason	原因状语

　　例：I shall never forget the day when (=on which) we first met.
　　我永远也不会忘记我们第一次见面的那一天。
　　The rain came at a time when (=at which) it was not needed.
　　雨下得不是时候。
　　This is the computer where (=by/on which) he has stolen top-secret documents.
　　这就是他用来盗窃绝密文件的计算机。
　　Here is the place where (=at which) the murder took place.
　　这就是谋杀发生的地方。
　　He didn’t give any reason why (=for which) I had been fired.
　　他没给任何解雇我的理由
　　This is the house in which (=where) my parents used to live.
　　这就是我父母以前住过的房子。