300.
M: Hello, Mary. How are you today? I heard you weren't well last week.
W: I'm much better now. Thank you.
M: What was the matter? Nothing serious I hope.
W: Oh, no. I had a bad cold and had to stay in bed for two days.
M: I'm glad you're better. Anyway, I hope it was the last cold of winter and not the first cold of summer. What about your friend, Ann? I hear she is ill, too.
W: She was ill. But she'll be all right now. I think she caught my cold.
M: Everybody seems to have one now. I expect it's the sudden change of weather. One day hot and the next day cold.
W: And very windy, too. That's why I'm wearing a sweater today. What do you think of it? Pretty, isn't it
M: It certainly is. It must cost a lot. Where did you find it?
W: Oh, I got it as a sale. It was quite cheap.
M: Really! Well, Mary, I must say, it suits you very well. What a pity we men can't wear beautiful sweaters!
W: Never mind. Let's go and buy one like it to send to your sister Linda in America.
M: That's very kind of you, Mary. I'm really thinking of sending her a present.

答案解析：
(1) 正确答案为A。根据I had a bad cold and had to stay in bed for two days.我患了重感冒，不得不在家休息了两天。可知，玛丽在家休息了两天，因此A项正确。
(2) 正确答案为C。根据Everybody seems to have one now. I expect it's the sudden change of weather. One day hot and the next day cold.好像现在大家都有感冒的症状。我想是因为天气突变的原因。一天热一天冷。可知，许多人患感冒的原因是天气突变，因此C项正确。
(3) 正确答案为C。根据女子说Let's go and buy one like it to send to your sister Linda in America.我们去给你在美国的姐姐琳达买一件吧。可知，琳达是男子的姐姐，因此C项正确。