WHICH/THAT and WHO/M ... 02
'You will recall from WHICH 03 that:
(a) 'qui' is generally used for 'who' or 'which' when it denotes the *subject* of a following verb.
(b) 'que' is generally used for 'whom' or 'which'/'that' when it denotes the *object* of a following verb.
(c) 'qui' is also used for 'who/m' (ie a person) when it follows a preposition (even if it is not the *subject* of a following verb).
This whole 'preposition' issue is a major factor in French. Particularly "de" ('of', or 'from') and "à" ('to', or 'at'), but we'll come to those (many times!) later. For now, the relevance of mentioning 'prepositions' is that 'which' [or 'that', meaning 'which'] is *different* when it follows a preposition. Instead of 'que' we have 'lequel', 'laquelle', 'lesquels', 'lesquelles' (and yes, each of these "agrees" with the noun it relates to).
|the exercise book in which I write
||le cahier dans lequel j'écris|
|the exercise books in which we write
||les cahiers dans lesquels nous écrivons|
|the chalk with which I draw
||la craie avec laquelle je dessine|
|the chalks with which we draw
||les craies avec lesquelles nous dessinons|
Just two more (tiny) points. Firstly, 'lequel', 'laquelle', 'lesquels', 'lesquelles' are only used for "things" (not people) *except* after 'parmi' (amongst) or 'entre' (between) - so logically you'd only expect to find the *plural* forms used for people. eg 'Les filles, entre lesquelles elle s'est assise, étaient belles.' ('The girls, between whom she sat, were beautiful.)
The second minor issue is a "usage" type of thing. Usually something like 'dans lequel' would actually be replaced by 'oś' (where). Not always, but often. So "le cahier dans lequel j'écris" would become "le cahier oś j'écris".