题目内容：

If you feel sleepy every morning, don't blame yourself. Your work schedule could be to blame.

A recent research shows that, for many of us, our work schedules do not agree with our natural body clocks—and experts are urging employers to take notice.

“When work schedules agree with people's natural sleep patterns, they produce higher quality and more creative work because they are more focused, less stressed and generally healthier. The opposite is also true—when employees are sleep deprived, they are more likely to make major mistakes and suffer from workplace injuries，” said Christopher Barnes, a management professor from the University of Washington.

“But it's not just about the amount of sleep you get. Whether you can be productive at 8 a．m. depends on your own body. Human beings each have an internal body clock，” said Till Roenneberg, a professor at Ludwig­Maximilian University in Munich. And that clock can differ greatly depending on the person.

“It's like feet，” said Roenneberg. “Some people are born with big feet and some with small feet, but most people are somewhere in the middle.”

Many companies start the work day at 8 a．m. or 9 a．m., putting their work schedules in disagreement with their employees' body clock. That mismatch, along with the pressure from work at all hours of the day and night, means that many people suffer from “social jetlag”. In other words, their bodies are always in the wrong time zone. He estimates that more than 70% of people get up earlier than they should.

“There is an old saying that sleep is for the weak，” said Roenneberg. “But I do feel like it doesn't help to have shortened sleep.”

1.According to the author, many people feel sleepy in the morning because________．

A. they start to work too early    B. they are not in good health

C. they have no interest in their work    D. they stay up too late the night before

2.What does Christopher Barnes mainly tell us?

A. The influences of lack of sleep.

B. The possible causes of poor sleep.

C. The useful ways to improve our sleep.

D. The connection between sleep and work performance.

3.By mentioning people's feet, Roenneberg intends to tell us ________．

A. people are born with feet of different sizes

B. people's body clocks differ from person to person

C. it is the most important to wear shoes of the right size

D. it is most important to obey our natural body clocks

4.Which of the following does the author agree to?

A. Sleep is for the weak.    B. The early bird catches the worm.

C. Plenty of sleep contributes to good work.    D. The more you sleep, the less work you can do.