一、适当形式填空(单句适当形式)（共5小题；共5分）
1. The book described the (adapt) of desert species to the hot conditions.
2. Mirella approached him and, after a brief (hesitate), shook his hand.
3. He had done the job (proper), which made his boss happy with him.
4. We invited 30 people, but only a (hand) of them came.
