Reléguer (mettre) au second plan = To put into the background.
Planche
Faire la planche = 1. To show others the way; 2. To float on one’s back.
C’est sa planche de salut = It is his last hope, his sheet-anchor.
Plancher
Le plancher des vaches (fam.) = Dry land; Terra firma.
Débarrasse-moi le plancher (fam.) = Get out of my way.
Planter
Vous m’avez planté là = You left me without any warning; You left me in the lurch.