________ mothers couldn’t go to the meeting, because they have gone to Shanghai .
After a pleasant summer vacation, the family came back from Beidaihe, _______.
I’d appreciate _______ if you could let me know in advance whether or not you will come.
By the time he gets home, his father _____________ for Pairs on business.
Never before in our country _______________.
—We'd better go downstairs right now for lunch.— ______ They serve food 24 hours a day.