—Must we keep the window _______ all the time?—No, you don’t have to.A.opening B.opened C. open
——Must we finish the exercise today? ——No, you________.
Your pocket money can be used to _____ charity, you used to _______ a lot on snacks.
The disabled people feel grateful _______ you ________ your help.
The old man should be treated with .
The children should go to school instead of to support their families.