Воткнуть who or which 1 she returned me the book.... i

Таким образом, и "who", и "which" в данном контексте переводятся как "который", но "who" употребляется с одушевлёнными существительными, "which" - с неодушевленными существительными.

1) She returned me the book which I gave her yesterday. 2) Do you know the student who has won the first prize in the competition. 3) The mother tongue is a language which a child learns naturally in her family. 4) I knew a lady who played tennis every day. 5) Kate found a bag which she liked.