1. By 2008, the environment here will be ____________ (更加舒适). 2. Do you know what the ____________ (目的) of learning English is? 3. In our country, we will never _____________ (挨饿) 4. In the past, each family had _____________ (至少) three or four children in our country. 5. I think ____________ (空气污染) is the most serious problem in the world.