1 . The book ___________（refer）to by the specialist at the meeting deals with Asian problems. (所给词的适当形式填空)

2 . Busily ________ (employ) in cleaning his shoes, he didn't notice my coming.

3 . __________ (expose) to Chinese culture in person, you will have a better understanding of it.

4 . ________ (face) with the threat of water shortages, Beijing and Shanghai are taking effective measures to save water and protect water resources.

5 . You should keep yourself __________________(inform)of what your son is doing. （用单词适当形式填空）

6 . We finally managed to make the customers _____________(convince) of the quality of the vehicle. (所给词的适当形式填空）