听一段材料，回答下面几个小题。How long did Mary stay in bed?
A. For 2 days.
B. For 3 days.
C. For 4 days.Why have so many people caught a cold?
A. Because of the cold weather.
B. Because of no heating.
C. Because of the changing weather.Who is Linda?
A. The woman's friend.
B. The woman's sister.
C. The man's sister.
