A week has seven days. ______ seven days in a week.

[A] It’s good always studying without enjoying oneself.
B. It’s good always enjoying oneself without studying.
C. It’ s good to study hard and enjoy oneself once in a while (偶尔).

[A] Because he and his friend were high in the sky.
B. Because he was looking down at the reflections of the stars on the surface of the water.
C. Because he was very happy to have passed the examinations.