stay the course

crash course

A quick, intense course of learning, especially one which is informal or hurried.

due course

Regular or appropriate passage or occurrence

let nature take its course

To permit events to proceed or a situation to develop without intervention or interference.

matter of course

A natural or logical outcome; perforce.

par for the course

To be expected; normal; common.

reverse course

To stop and proceed in the opposite direction.

stay away

To avoid or not go anywhere near someone or something.

stay behind

To remain where one is, whilst others leave.