根据句意，用括号内所给动词的适当形式填空。

1. You shouldn't have _____ (leave) so soon at the party.

2. He is _____ (suppose) to arrive at the station at 8:40.

3. They lay on the beach, _____ (look) up into the blue sky.

4. Eating dumplings at the Spring Festival _____ (be) the custom in our country.

5. I was very embarrassed at the party because I _____ (wear) the wrong clothes.