TO CALL OFF

TO CALL OFF (V):  to cancel

• The commander called off his soldiers and surrendered.
• Call the policeman off from the place of crime, they just evoke panic among people.

TO KNOCK

TO KNOCK (V): to make a noise by hitting something with your close hand

• Somebody's knocking at the door. That'll be the postman.
• Children were knocking on the window to annoy their nasty neighbour.

FENCE

FENCE

• Our small dog kept running into the street, so we decided to build fence around the house.
• They escaped by jumping the fence, which was not very high.

POLLUTION

POLLUTION

• Something has to be done to prevent further environmental pollution.
• Exhaust fumes and harmful wastes cause a lot of pollution these days.

FIREFIGHTER

FIREFIGHTER

• There were 50 firefighters trying to save people from the burning office building.
• When they saw the firefighters driving in the direction of their house, they expected the worst and they were right: their house was in flames.

MARK

MARK

• The highest mark in the exam was 35/50.
• I used to get very good marks when I was at secondary school. However, I didn't do that well at university.

GRADE

GRADE

• Did you get good grades when you were at school? Yes, I was really hard-working.
• Have you already got a grade for your essay?

keep the change

keep the change: don't give back any money that has been overpaid, perhaps as a tip, or because the amount is so small

• I bought a newspaper at the airport with my last Brazilian reals, so I told the seller to keep the change.

keep to the subject

keep to the subject: talk or write only about the immediate topic

• I know you want to talk about vacation plans, but please keep to the subject while we figure out the answer to this other problem.

keep (something) in mind

keep (something) in mind: remember a fact or piece of information, especially because it might be useful in the future

• You need to be at the airport two hours early now - keep that in mind when you leave for London.