14. The atmosphere()certain gases mixed together in definite proportions.

19、The children _______ play with them.

18、Who should be responsible ______ the loss of the documents?

17、Farmers use water in many ways. ________, they use water to grow crops.

16、Fish can＇t live ______ water.

15、I am going to _______ the meal, I insist.

14、A long time ago, I _______ in London for three years.

13、We should not look down ________ the poor people.

12、It is because he is kind and modest ________ he wins the respect of all presents.

11、He helped me ______ my homework.

10、These flowers ________ a fragrant perfume.