Readers are required to _________ the rules of thelibrary and mind their manners.

下列各句中，没有语病的一句是

The experiment shows that proper amounts of exercise, if _______ regularly, can improve our health.

My daughter doesn’t know what to ______ at the university. She can’t make up her mind about her future.–You should give her some suggestions.

s like riding a bicycle. _____ your balance, you must keep moving.