填空题。
1. A _____ sea has no, or only small waves, and a _____ film has no speech.
2. There is an article that _____ the rise of the prices. (concern)
3. The children are rather _____ about their mother's health. (concern)
4. Officials should _____ themselves _____ public affairs. (concern)
5. During his last lecture, the scientist _____ (觉得) easier to explain the theory
to those with some background knowledge. (find)
6. We're going to play basketball. Would you like to _____? (join in / attend)