A、Mow the lawn. B、Water the house plants. C、Take care of her pets. D、Take care of her children. C文中指出，当艾力克帮科恩先生看家的同时，还要帮她照顾宠物，故答

M: Hey, any idea of what to do this summer vacation? There doesn’t seem to be any jobs available.
W: (19)Why don’t you try house-sitting? Last summer my friend Marsha house-sat for the Howards when they went away on vacation.(20)Mr-Howard hired Marsha to stay in their house because he didn’t want to leave it empty.
M: You mean the Howards paid Marsha just to live in their house?
W: It wasn’t that easy. She had to mow the lawn and water the house plants.(21)And when Eric house-sat for Dr. Cohen, he had to take care of her pets.
M: House-sitting sounds like a good job. I guess it is a little like baby-sitting except you take care of a house instead of children.
W: The student employment office still has a few jobs posted.
M: Do I just have to fill out an application?
W: (22)Margaret and Eric had the interview with the homeowners and provided three references each.
M: That seems like a lot of trouble for a summer job.
W: Well, the homeowners want some guarantee that they can trust the house-sitter. You know they want to make sure you’re not the type who’ll throw wild parties in their house, or move a group of friends in with you.
M: House-sitters who do that sort of thing probably aren’t paid then.
W: Usually they’re paid anyway just because the homeowners don’t want to make a fuss. But if the homeowner reported it, then the house-sitter wouldn’t be able to get another job. So why don’t you apply?
M: Yeah, I think I will.
19. What does the woman suggest the man do in the summer vacation?
20. What did the Howards do when they went away last summer?
21. What did Dr. Cohen ask Eric specifically to do when he house-sat for her?
22. How do homeowners decide to hire a house-sitter?