If you sit in a chair _____a long time, your back may begin to hurt.
There are ______ rules in my family, so what can I do?
—It is useful book!—Yeah, it tells you how to play guitar.
——What is Grace doing?——She _____ in the pool.
——Can you speak English well?——________. but I can also speak Chinese well.
——Our English teacher is strict ______ us.——I think they’re good ______us.