To save energy, don’t forget ________ the light before you leave the room.
turn off
turning off
to turn off
When I was walking in the street yesterday,I saw a UFO________over my head.
Many books________about“the art of giving”;you can buy one for yourself.
The clothes are aimed________teenagers.
Remember________your host’s suggestions and________the rules.
Pandas are________animals in the world.We must do something to protect them.