Relative pronouns - advanced

Advanced relative pronouns extend basic use to more formal or precise structures: restricting vs non-restricting clauses, preposition placement, omission, and special forms (whose, whom, of which). They help link clauses and add essential or additional information about a noun (the antecedent).

• Distinguish restrictive (essential) and non-restrictive (additional) clauses.
• Decide when to use who/whom, whose, which, that, where, when, why and 'of which'.
• Place prepositions formally before the relative pronoun (to whom) or informally at clause end (who/which ... to).
• Know when omission of the pronoun is allowed (object of a restrictive clause).

Key rules for advanced usage:

• Use commas for non-restrictive clauses (additional info) and 'which' or 'who' — The CEO, who is based in Berlin, visited.
• Use 'that' for restrictive clauses (essential info) without commas — Documents that are signed are final.
• Place the preposition before the pronoun in formal writing: the partner to whom we replied.
• Use 'whom' for formal object positions after prepositions; omit the pronoun when it is the object in restrictive clauses for more natural speech.

Formality affects choices: 'whom' and 'of which' are common in formal or written contexts.

Avoid these universal errors:

• Using 'that' with commas in non-restrictive clauses — commas indicate an additional remark, so use 'which' or 'who'.
• Omitting the pronoun when it is the subject of the clause — omission is only possible when the pronoun is the object.
• Placing the preposition incorrectly after the relative pronoun in formal writing — prefer 'to whom' over 'whom ... to' in formal texts.
• Confusing who and whom — who = subject; whom = object (especially after prepositions).
• Using 'which' for people — use who/whom for people.

These mistakes are common across learners; focus on clause type (restrictive vs non-restrictive) and the pronoun's function (subject/object).