1. Why is headache a common disease in the USA ? 2. can people see when they have headaches? 3. May people have pains on only one side of the head? 4. When do people have headaches? 5. How can people prevent headaches?

`1`.Because about fifty million people have to go to the doctor every year

`->` Thông tin : " Every year ... because of headaches "

`2`.They can see black dots or bright sports in front of their eyes

`->` Thông tin : " People can see ... front of their eyes "

`3`.Yes , they may

`->` Thông tin : " They may also ... side of the head "

`4`.When they work too hard or they are too nervous about something

`->` Thông tin : " People have headaches ... nervous about something "

`5`.By changing their diets or their lifestyle or simply by going to bed

`->` Thông tin : " They can prevent ... by going to bed "

`\text{# TF}`