1 . When your alarm clock rings and you drag yourself out of bed, you probably wonder： Why on earth does school have to start so early?

Fortunately, there is a new law to support—or better still, science.

A law in California, passed on Oct 13, requires that public middle schools begin classes no earlier than 8：00 am and that high schools start no earlier than 8：30 am. The law will go into effect by July 1, 2022.

Starting school at 8：00 or 8：30 in the morning may not sound like too big of a change, but it could mean one more hour of sleep for students who used to start school at 7:30 or even earlier.

"The effect of that one hour is something they will be feeling as 40-year-old adults," Sumit Bhargava, a sleep expert at Stanford University, told The New York Times. He said that not having enough sleep can affect students' mental health and increase the risk of being overweight and diabetes （糖尿病）.

In the short run, students' school performances should improve almost immediately. Kyla Wahlstrom, a researcher at the University of Minnesota's College of Education, found that students who have enough sleep are alert in class and get much more satisfying grades.

Some might say that asking students to go to bed earlier could have been a much easier solution than changing the school timetable across an entire state. But according to the American Academy of Sleep Medicine, teenagers go through biological changes when they enter puberty （青春期）,which makes it difficult for them to fall asleep before 11：00 pm. So when school starts at 8：00 or earlier, they can hardly get the ideal 8.5-9.5 hours of sleep that experts suggest they need to do their best in the daytime.

This is why when the new law came out, its author, Anthony Portantino, said, "Generations of children will come to appreciate this historic day and our governor for taking action."

1. Which of the following is TRUE about the law?

A．The law has not been put into practice.

B．The law requires schools to start later than 8：30am.

C．The law will be passed by July 1, 2022.

D．The law is made by a university in California.

2. What does the underlined word alert in Paragraph 6 probably mean?

A．Friendly.	B．Sharp.
C．Calm.	D．Honest.

3. For a better academic performance in the daytime, how long do teenagers probably need to sleep?

A．About 8 hours.	B．About 9 hours.
C．At least 10 hours.	D．At most 8. 5 hours.

4. What's the main idea of the text?

A．Lack of sleep could lead to health problems.

B．The amount of sleep people need changes with age.

C．A new law lets students sleep longer.

D．Sleeping problems are leading problems for teenagers.