Headaches can be very painful and can last for a long time.

If you have a headache, your head hurts.

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A sprained ankle can be so painful that you can't walk.

Someone with the sprained ankle may need to use crutches to walk.

备注：sprained ankle[医] 踝关节扭伤;

         sprain可作动词用，vt. 扭伤（关节），亦可用作名词，n.扭伤  

例句：He fell and 

sprained his ankle.

他摔了一跤，扭伤了脚踝。

 crutches：拐杖( crutch的名词复数 ); 支持物; 精神上的寄托; 胯部;

 crutch：n.拐杖; 支持物; 精神上的寄托; 胯部; vt.支撑; 支持;

I can walk without the aid of 

crutches

我不用拐杖也能自己走。

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If you have a sore throat, it may be painful to  swallow.

A sore throat can be caused by viruses or  bacteria.

When you have a sore throat, the back of your throat is often red and infected.

sore: adj.疼痛的; 使人伤心的; 恼火的，发怒的; n.（肌肤的） 痛处，伤处;

 

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A burn is an injury to the skin caused by fire or heat.

If you get too close to a fire you will be burned.

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An earache is a sharp, dull or burning pain in the ear.

Common causes of an earache include an infection, a change in air pressure or water in the ear.

耳朵痛;

dull : adj.迟钝的; 钝的; 呆滞的; 阴暗的; v.缓和; 减轻; 使阴暗;

dull一般用于表示迟钝的，在这里钝痛（dull pain）指一种性质与刺痛、刀割样痛相反，而呈不太尖锐的疼痛。