. These students will graduate from the university next summer, ________ they will have studied here for four years.
20. When Jack arrived, he learned Mary ____ for almost an hour.
19. They didn't _____ the wedding because of a heavy rain.
18. Don't worry! He ____ no attempt to leave. He will stay here to help you.
17. --- Will someone go and get Mr. White? --- He’s already been ____ .
16. It is reported that they ____ arms and began to fight against the invaders (侵略者).