"People of all walks of life are welcome to ________ the hope project," said the poster.
19. The best job is _______ which uses your skills in doing something together with your interest in the subject.
20. In the past ten years, great changes _______ in my hometown.
21. The third and last chapter _______ by Professor Chen.
22. --- No, I’m afraid he isn’t in. This is his secretary speaking. Can I help you? --- _______.
23. _______ the plane have taken off on time? --- I’m afraid not. The fog was too thick then.