根据短文内容，完成下列各小题。

    It's four thirty in the afternoon. There are many students on the playground. Jim and his friends are playing basketball. Li Lei and other boys are playing football. Miss Gao is watching the games. She is looking after the clothes, too. Where are the girls? They are over there. Some are running, others are jumping. The twins are on duty today. They are in the classroom. Lucy is cleaning the window, Lily is sweeping the floor. They are working hard. They are tired(疲倦的) but happy.

下列关于张居正改革背景的叙述，最准确的是