Choose the necessary word.
1) the Oka is a (deep/deepen) river. The farmers plan to (deep/ deepen) the lake next year.
2) The night was (dark/darken) when we were returning home. Please, (dark/darken) the room, I am going to show you the film "New York".
3) I don't like the (length/lengthen) of your coat. You should (length/lengthen) it a little.