听一段材料，回答下面几个小题。
Where is Sally?
A. At home.    B. At Betty’s home.     C. At a shop.
Whose birthday is next Friday?
A. Dave and Sally’s.
B. Dave and Betty’s.
C. Sally and Betty’s.
When is Dave’s birthday party?
A. At six o’clock.
B. At half past six.
C. At seven o’clock.