1. The expert concluded that the broken engine was difficult to repair.  He drew the conclusion by analysing the research data. (conclude)

2. In a way,   challenges are good for developing our strong characters and I like doing various challenging  jobs. (challenge)

3. The tourist attraction is polluted badly.  The local government is taking measures to deal with the pollution of this place. (pollute)

4. The announcer interviewed the mayor,   who announced that the tourism of this place was developing quickly. His announcement made local people happy.  (announce)

5. An instructor used unique methods to instruct his students to draw cartoon characters. He also asked them to follow his instructions. (instruct)