V. 单项选择：从下列各题所给A、B、C、D四个选项中选择一个可以填 入空白处的最佳答案。15分。
26. Don’t just concentrate on your study. Be more ______ in school activities.
A. active B. calm C. serious D. careful
27. －Why didn’t Susan come to the party?
－Perhaps she ______.
A. didn’t invite B. hadn’t invited C. won’t be invited D. wasn’t invited
