The number of people invited ______ fifty, but a number of them _____ absent for different reasons.
It is impolite to sit there with your feet _____ at somebody.
Sam________some knowledge of the computer just by watching others working on it.
If the babysitter cannot come tomorrow,do you mind________alone at home,doing his homework?
Now that you’re grown up,you’d better spend your time just on the things you find_______.
The city government is planning to build a factory to deal with the industry waste,but when and where to build it________.