Kill two birds with one stone: produce two useful results by just doing one action.Examples: Biking to work kills two birds with one stone. It saves money travelling and will help to lose weight. John learned the words to his part in the play while peeling potatoes. He was killing two birds with one stone.

to keep up: to prevent from sleeping; to continue maintaining (speed, level of work, condition, etc.) Examples of TO KEEP UP If we can keep up this speed, we should arrive there in about three hours. That student has been getting all As. I hope he can keep it up.

to step down: to retire or leave a top position, to resign Examples of TO STEP DOWN Next May the principal will step down after thirty-five years of service to the school. The angry shareholders wanted the company president to step down because of the stock scandal.

to make up one’s mind: to reach a decision, to decide finally Examples of MAKE UP ONE’S MIND He needs to make up his mind what restaurant to go to, otherwise we’ll never eat. She can’t make up her mind between two great jobs.

to feel sorry for: to pity, to feel compassion for (also: to take pity on) Examples of TO FEEL SORRY FOR Go meet someone; it’s time to stop feeling sorry for yourself after your divorce. I’m not able to feel sorry for your financial problems – you knew you’d have to pay your credit card…

out of the question: impossible, not feasible Examples of OUT OF THE QUESTION Buying a new car is out of the question, especially before we pay off the old car. If we close this deal, a raise wouldn’t be out of the question for you!