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.