`#V``i``n``n``y``/V``i``n``tr``i``cz`

`1. C`

`⇒` symptoms of smth : triệu chứng của cái gì đó.

`2. B`

`⇒` Chủ ngữ "people" là số nhiều dùng "have"

`3. A`

`⇒` have a headache + when + they + V(0/inf) : bị đau đầu khi họ làm điều gì đó

`4. A`

`⇒` Medicine can help smth : thuốc có thể giúp gì đó.

Headache is a very common disease. The symptoms of a headache are various. People may  have pains only one side of the head. Sometimes when the pain goes away, the head is sore. People have a headache A. when they work too hard or they are too nervous about something. Medicine can help cure the disease but people usually have to do more than taking tablets. They can prevent headaches by changing their diets or their lifestyles or simply by going to bed.