--- Can you tell me where Tom is? --- He ________ on the playground. A. plays B. playing C. is playing
They have been friends __________ they were at primary school.
I’ll go to visit my uncle in England ________ the winter holidays start.
The mobile phone has changed people’s life a lot ________ it was invented.
Getting enough sleep is good for _______ health _______ study.
— Hey, boy. You can’t cross the street now. You have to wait _______ the traffic lights turn green. — Oh, sorry and thank you.