作业精灵老师示例：
1.—What time is it？
—It's seven o'clock. It's time for breakfast.
2.—What time is it？
—It's ten o'clock. It's time for class.
3.—What time is it？
—It's twelve o'clock. It's time for lunch.
4.—What time is it？
—It's six o'clock (in the afternoon). It's time for dinner.
5.—What time is it？
—It's nine o'clock (in the evening). It's time for bed.
