I am totally hung up on relative pronouns, partcularly 'that' and 'what'. Can anyone explain (as simply as possible) how they work?
Relative pronouns are that, who, whom, whose, which, where, when, and why. They are used to join clauses in between to make a complex sentence. Relative pronouns are used at the beginning of the subordinate clause which gives some specific information about the main clause.
This is the house that Jack built.In English, the choice of the relative pronoun depends on the type of clause it is used in. There are two types of clauses distinguished: defining (restrictive) relative clauses and non-defining (non-restrictive) relative clauses. In both types of clauses the relative pronoun can function as a subject, an object, or a possessive.
I don't know the day when Jane marries him.
Mike never tells me where he is going.
The relative pronoun that can only be used in defining clauses. It can also be substituted for who (referring to persons) or which (referring to things). That is often used in speech; who and which are more common in written English.
William Kellogg was the man that lived in the late 19th century and had some weird ideas about raising children. - spoken, less formalAlthough your computer may suggest to correct it, referring to things, which may be used in the defining clause to put additional emphasis on the explanation. Again, the sentence with which is more formal than the one with that: Note that since it is the defining clause, there is NO comma used preceding which:
William Kellogg was the man who lived in the late 19th century and had some weird ideas about raising children. - written, more formal
The café that sells the best coffee in town has recently been closed. - less formal
The café which sells the best coffee in town has recently been closed. - more formal
that / who
Referring to people, both that and who can be used. That may be used to referring to someone in general:
He is the kind of person that/who will never let you down.However, when a particular person is being spoken about, who is preferred:
I am looking for someone that/who could give me a ride to Chicago.
The old lady who lives next door is a teacher.
The girl who wore a red dress attracted everybody's attention at the party.
that / which
There several cases when that is more appropriate than and is preferred to which:
After the pronouns all, any(thing), every(thing), few, little, many, much, no(thing), none, some(thing):
The police usually ask for every detail that helps identify the missing person. - that used as the subjectAfter verbs that answer the question WHAT? For example, say, suggest, state, declare, hope, think, write, etc. In this case, the whole relative clause functions as the object of the main clause:
Marrying a congressman is all (that) she wants. - that used as the object
Some people say (that) success is one percent of talent and ninety-nine percent of hard work.The chairman stated at the meeting (that) his company is part of a big-time entertainment industry.After the noun modified by an adjective in the superlative degree:
This is the funniest story (that) I have ever read! - that used as the object
After ordinal numbers, e.g., first, second, etc.:
The first draft (that) we submitted was really horrible. - that used as the objectIf the verb in the main clause is a form of BE:
This is a claim that has absolutely no reason in it. - that used as the subject