1 . There is a ________ (regularly) bus service to the airport. (所给词的适当形式填空)

2 . The book provides ________ (value) information on how to learn English well. （所给词的适当形式填空）

3 . Working this way for one year was________ (pain) enough, let alone a lifetime. Before long I decided to make a change. (所给词的适当形式填空)