Ⅴ. 补全短文。
根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有一项为多余选项。
Why are you always tired? Do you know? 1.
First, if we can't sleep well, we will be tired. But we are often too busy. We can't finish our homework or work in the day so we have to do it at night. We go to bed late and we get up early in the morning for school or work. 2. If we sleep for only five or six hours a night, we will be tired.
Next, when we are ill, we will be tired. But we don't know we are ill. So if you are always tired, maybe you are not so healthy. 3.
Then, maybe you eat too much food, like hamburgers, meat, chocolate or coffee. If you are ill and tired after eating some food, please don't eat it again. 4.
At last, if the air around you isn't nice or clean, you will feel tired. 5. And then you will feel better.
After feeling tired, you can take a short break, drink some water or take a shower, especially before you sleep at night.
A. You'd better go to see a doctor.
B. I will tell you some reasons about it.
C. But you can eat some if you are well.
D. Most people need at least eight hours of sleep or some more.
E. So please open your windows often or go out for a walk.
F. Do you have enough homework every day?

1.B 2.D 3.A 4.C 5.E

1. 空前提出问题“你知道为什么总是感觉疲惫吗？”，后文开始逐一介绍疲惫的原因，B选项“我会告诉你一些相关的原因”起到总起下文的作用，符合语境。
2. 空前提到我们晚睡早起，空后说明每晚只睡五六个小时就会疲惫，D选项“大部分人至少需要8小时甚至更长的睡眠时间”衔接上下文，解释了睡眠不足会导致疲惫的原因，符合逻辑。
3. 空前指出如果总是疲惫，可能身体不够健康，A选项“你最好去看医生”是对应身体不适的合理建议，符合语境。
4. 空前说明如果吃完某些食物后不舒服、感到疲惫，就不要再吃这类食物，C选项“但如果你身体状态良好，你可以吃一点（这类食物）”语义转折，衔接自然。
5. 空前提到如果周围的空气不好、不干净你会感到疲惫，空后说之后你会感觉好很多，E选项“所以请经常打开窗户或者出去散散步”是对应空气不好的合理解决办法，符合语境。多余选项F不符合文章逻辑。