19. They________a lot of suggestions for improvingthe workers’ living conditions.

Why are you angry with Michael— Because I waited for him for two hours last night, but he didn’t _______ at last.

According to my mother, it is a good idea to have some chicken soup when you have a cold．—_____, scientists agree with her．

Did Peter fix the computer himself—He ________ because he doesn’t know much about computers.

an hardly boil an egg, still _____ cook dinner.