Be quiet, the head teacher Mr. Gu is coming.— Don’t worry. It _____ be him. Mr. Gu is much fatter.

Do you like _______when someone speaks toyou without looking at you

To live on Mars, you need to wear boots which ________ to prevent you from floating off into space.

Parents and teachers should help teenagers control their use of computer games ______be controlled by themselves

I can see ______ oranges, but I can’t see ______ apples.