American students have ______ weeks ______ in summer holiday than Chinese students.

Have you heard about Volunteer? —Sure, A volunteer is someone _________ is willing to offer help without being paid..

Peter, _____ do you visit your grandparents?—Twice a month.[ ]

Wearing red can make ______ easier for us to take action.

You know a lot about Chinese history, don’t you?–Yes, I ___________ China for a long time since 1998.