题目内容：

    If you've ever stayed up late and then got up early the next day, you know what it's like to not get enough sleep. It's a very uncomfortable feeling. In fact, scientists have long believed that sleep is like food ——if we don't get enough of it, we might get sick or even die. But now they are starting to wonder just how much sleep we need.

Researchers from London recently did a study on fruit flies （果蝇）. They found that flies that slept for very short periods of time —— about 72minutes a day —— still lived about as long as flies that slept for longer time. One of the flies slept for just 4 minutes each day. This has led the researchers to wonder if sleep is less necessary than we thought before.

Humans are very different from fruit flies. Sleep is when our bodies do a lot of work, for example, repairing tissue（组织）and growing muscle （肌肉）.Sleeping allows our bodies to get a good rest.

But can we really die from not sleeping? No human has died so far from staying awake for too long. The world record for sleeplessness is held by Randy Gardner from the US, who stayed awake for 11 days and 24 minutes in 1964. However, Gardner did experience serious side effects （副作用）.

Scientists have not yet found any animals that don't sleep at all. Even animals that only sleep for short periods are not completely sleepless. This suggests that a short sleep is necessary, even in short-sleeping animals, according to a German scientist.

1.What does the study on fruit flies show?

A.Fruit flies sleep less than humans do.

B.Flies need 72 minutes of sleep every day.

C.Sleep is as necessary for animals as it is for humans.

D.Getting less sleep doesn't seem to influence how long flies live.

2.The purpose of Paragraph 3 is to________.

A.describe how much sleep humans need B.explain why sleep is important to humans

C.list the differences between humans and flies D.show the similarities between flies and humans

3.What do we know from the passage?

A.Sleep may not be so important as we think it is. B.Humans need more sleep than animals.

C.Sleeplessness can lead to death. D.Not all animals need sleep.

4.What’s the best title for the passage?

A.How Much Sleep? B.Die Without Sleep.

C.Wonders of Nature. D.Get Enough Sleep.