用括號內所給單詞的適當形式填空。
1. You are ____ (suppose) to keep silent when the teacher is speaking in class.
2. When I was introduced to the American professor, we __ _ (shake) hands with each other.
3. People_______ (drop) by each other's house on the Spring Festival.
4. I feel very _______ (relax) when I listen to my favorite music.
5. They usually make plans __ (see) friends.
