Breakdown of Je déplace le coussin sur lequel tu dors.
je
I
tu
you (informal singular)
sur
on
dormir
to sleep
Questions & Answers about Je déplace le coussin sur lequel tu dors.
Why do we use sur lequel here instead of que or qui?
In French, when you need to say 'on which', 'with which', or 'for which', you must use a preposition followed by a form of lequel. Relative pronouns like que (that/which) and qui (who/which) cannot be used directly after simple prepositions like sur when referring to things.
Why is it lequel and not laquelle or lesquels?
Lequel changes its form to match the gender and number of the noun it replaces. Here, 'which' refers to le coussin (the cushion). Since coussin is masculine and singular, you use the masculine singular form: lequel. If you were moving a feminine object like a chair (la chaise), it would be sur laquelle.
Could I use bouger instead of déplacer to say 'I am moving the cushion'?
As a refresher, why does dors end in an 's'?