Mr Smith has two______ , both of whom are teachers in a school.
________knowledge a man has,________it is for him to get a good job.
Many chemical substances react________oxygen.
The population of China ________ 1.3 billion,and 80% of the population________farmers.
They are quite different ________ each other ________their tastes.
He ________to come at eight, but in fact he never comes before nine.