单项选择题
A. Meet her Mum at the airport. B. Say good-bye to her Mum at the airport. C. Fly to another city together with her Mum.
A. Because they are better educated. B. Because they have less spare time. C. Because they are stronger. D. Because there are more young people.
A. The number of insects are larger than that of any other kind of animals. B. Silk worms and bees are useful insects to man. C. Insects are of no value to people. D. Insects live in all kinds of ways.