Lack of sleep among children and teenagers in China has worsened in the past years, especially on school days.

    More than 95 percent of students in primary schools, nearly 91 percent of those in middle schools do not get enough sleep on school days, increasing the risk of developing mental and physical health problems, the report said.

    About the COVID-19 epidemic's influence on sleep, research had shown that there were no great differences in sleeping time of students before and after schools reopened in China.

    All primary and middle school students in China will be banned（禁止）from bringing mobile phones to school, the Ministry of Education announced on Monday.

    , making sure they center on study and stopping them from becoming lost in the internet and online games.

    Dai Hanyang, a student in Changsha said, "I am not good at self-control, so not having my mobile phones with me helps me focus on studying."

    Zhang Ting, the mother of a fourth grader in Beijing, said, "A smart watch is more than enough for communication and the knowledge found in books is enough".

Ye Ting was excited when she learnt that her daughter's school would reduce the amount of homework so that students can have more free time, but her excitement did not last long.

    Minister of Education Chen said one of the ministry's main tasks this year is to limit the amount of homework for primary and middle school students and make sure they can enjoy free time and enough sleep for their healthy development.

, so they gave themselves more exercises or went to extra classes to learn more.

A. Students will have more free time to enjoy themselves

B. Many students don't have enough time to sleep

C. Schools ban students from bringing mobile phones

D. Many students started to worry they might be left behind

E. The news aimed at（旨在）protecting students' eyesight

F. Less homework fail to reduce students' pressure