“These are my pupils which I have brought to see you.” Use whom, as which is not applied to persons.
“This is the window whose panes were broken by the rude boys.” Use “the panes of which.” Because of its convenience, perhaps, the faulty whose is very largely used; as, “The eagle whose wings,” “The house whose gables,” “The ocean whose waves,” “The vessel whose sails,” “The play whose chief merit,” “Music whose chief attraction,” etc.
Which and who cannot follow and unless there has been a preceding which or who in the same sentence and in the same construction.
“The more important rules, definitions and observations, and which are therefore the most proper to be committed to memory, are printed with a large type.”—Murray’s Grammar. In Moore’s Bad English the sentence is corrected thus: “The rules, definitions, and observations which are the more important, and which are therefore the most proper to be committed to memory, are printed in larger type.”
Adverbs for Relative Pronouns
Adverbs are often employed where a preposition with a relative pronoun would better express the sense.
“There is no method known how his safety may be assured.” Use by which instead of how.
“He wrote me a letter where he repeated his instructions.” “Letter in which he repeated,” etc.
“And curse the country where their fathers dwelt.” “In which their fathers dwelt.”