call off (separable): cancel something that has been scheduled.

"We don't have school today. The mayor called classes off because of the snow."

call on (inseparable): ask someone for an answer in class.

"I don't know why the teacher never calls on you. You always know the answer."

calm down (with or without an object; with an object, separable): become calm / less agitated or upset; help someone become calm / less agitated or upset.

"Why are you so upset? Suzie didn't intend to spill orange juice on you. Calm down!"

"I know Ralph is upset, but can you calm him down? He's making so much noise that he's irritating everyone in the office."

(not) care for (1. inseparable): like; want.

Note: This phrasal verb is usually negative, though it may be used affirmatively in questions.

A: "Would you care for something to drink? We have coffee, tea, or orange juice."

B: "Could I have water, please? I don't care for coffee, tea, or juice."

care for (2. inseparable): take care of; supply care to; attend / watch..

"Amy's father got out of the hospital last week. The family is caring for him at home."

catch on (no object): develop understanding or knowledge of something.

"Bill had never used a computer until he took this class, but he caught on very quickly and is now one of the best students."

catch up (with) (often without an object; with an object, inseparable): stop being behind.

"Terry stopped to rest for a few minutes. He'll catch up / catch up with us later."

check in(to) (inseparable): register for / at a hotel, conference, etc.; let someone know officially that you have arrived.

"My plane will arrive around 5:00 PM. I should be able to check into the hotel by 6:00 or 6:30."

"When you arrive at the convention, be sure to check in at the registration desk."

check off (separable): make a mark to indicate that something on a list has been completed.

"Here are the things you need to do. Please check each one off when you've finished it."

check out (of) (1. inseparable): follow procedures for leaving (a hotel, etc.)

"Don't forget to take your room key to the front desk when you check out (when youcheck out of the hotel)."