We should plant more trees on       sides of the street.

Do you think        necessary to do a bird count ?Yes , we must count them at least once a year 

Miss Gao is our English teacher. She gives ____ a lot of help.

— Who will teach _______ oral English next term? Can it be a new teacher?— Perhaps. But our head teacher hasn't told us ________ .

--- Is this your sister’s key, John?--- No, it isn’t. ______ is in the bag.