题目内容：

Using a mobile phone before going to bed can damage your health, according to a major study.

It says that radiation from the mobile phone can cause insomnia(失眠症) and headaches as well as cutting the time spent in deep sleep. Failing to get enough sleep can lead to depression, lack of concentration and personality changes. In teenagers and young children, lack of sleep can result in attention disorders and poor grades.

The research showed that using mobile phones before bed causes people to take longer to reach the deeper stages of sleep and to spend less time in them.

Deep sleep is important as it is the time when the body rejuvenates(更新) cells and repairs damage suffered during the day. Scientists found that using mobile phones an hour before sleep affects it. In the study scientists examined the sleep patterns of 36 women and 35 men aged 18 to 45. Some were exposed to radiation that is similar to what a person receives when using a mobile phone. The others received none. The results are as follows: The first group took longer to enter the first of the deeper stages of sleep and spent less time in the deepest one. However, the second group was opposite.

The findings will shock many parents. Many parents are always worried about their children’s health. But they didn’t have a better way to persuade them not to use a mobile phone.

1.The passage mainly tells us that ________.

A. deep sleep is good for your health

B. using a mobile phone before sleep can damage your health

C. different people have different sleep patterns

D. long sleep can renew cells

2.The underlined word “ it”refers to ________.

A. people’s body    B. deep sleep

C. a sleep pattern    D. a day

3.Which of the following is NOT mentioned in the passage?

A. Deep sleep is a good time for the body to repair damage suffered during the day

B. The study examined the sleep patterns of about 70 people.

C. The findings shocked many teachers and teenagers.

D. Using mobile phones before bed causes people to take longer time to enter the deep sleep.

4.We can infer from the passage that _________.

A. the lack of sleep can lead to children’s excitement

B. radiation from the mobile phone can cause parents’ worries

C. many children use mobile phones before sleep

D. using a mobile phone before sleep doesn’t harm the aged