题目内容：

In winter，when the sun hides behind the clouds，everyone feels a bit low. You may be tired and find you want to sleep all the time. What you may not know is：you are suffering from (患有) SAD(季节性抑郁症)．

But don't worry—it's normal. Colder temperatures and fewer hours of daylight can steal your energy and put you in a bad mood.

Read on to find out what SAD is and what you can do to help yourself or those around you.

These days，Linda，a US teenager spends most of her holidays sleeping instead of doing sports outside. She has also had trouble concentrating(集中精力) on her homework. When her mother asks her what's wrong，Linda doesn't know what to tell her. Linda may not realize it yet，but she's suffering from SAD. It causes people to sleep，eat sweet food and get sad or angry for no reason.

About 15 percent of American people now suffer from SAD in winter according to the US Department of Health. The US government has taken measures to help people beat it. Local communities encourage people to take part in activities such as exercise，dance or art. And they advise people not to eat too much sweet food.

Like in the US，cold northern European countries such as Finland，Iceland and Russia see a large number of people suffer from SAD every year. So，the sunlamp is widely used in these countries. It's an electric lamp which is just like a “little sun” that gives off light to make people think the sun is shining and feel better.

1.Colder ________ and less ________ are the main causes of SAD.

2.Linda is feeling ________ and doesn't ________ doing sports because she's suffering from SAD.

3.      people suffer from SAD in        northern European countries.

4.In some northern European countries，the ________ is widely used to make people feel____ .

5.Taking an active part in ________ and eating ________ sweet food can help people beat SAD.