Keep one`s cool

To stay or remain calm.I tried to keep my cool during the argument with my neighbor.

Keep one`s chin up

To be brave, to be determined."Try and keep your chin up. Things will be better in the future."

Keep on one’s toes

To stay alert and watchful.I try to keep on my toes when the teacher may ask me a question.

Keep on (doing something)

To continue doing something.The girl is careless and keeps on making the same mistakes over and over.

Keep on an even keel

To remain cool and calm.I was busy with my job and school but I tried hard to keep on an even keel and get everything done.

Keep off (something)

To stay off someone's land or other property.The students were asked to keep off the grass which was being replanted.

Keep late hours

To stay up late, to stay out until very late.My friend keeps late hours now that he is working for the newspaper.

Keep in touch (with someone)

To talk or write to someone, to maintain contact with someone.I have always tried to keep in touch with my friends from high school.

Keep house

To look after a house or a household.The girl has been keeping house for her father while he is sick.

Keep harping on (something)

To continue to talk or complain about something.The boy's father keeps harping on the fact that his son never does his homework.