1. This toy Is not____(suit) for young children. 2. There____(use) to be a lot of birds here, but now we can hardly see them. 3. The heavy rain stopped the visitors____ (climb) the mountain. 4. They often collect waste paper and bottles for____(recycle) to protect the environment, 5.--What"re they doing? --They"re____ (wait) for a bus.