Headache can be very painful and can last for a long time. If you have headache your head hurts.

A sprained ankle can be so painful that you can’t walk. Someone with a sprained ankle may need to use to crutches to walk.

Crutches

n.拐杖;支持物;精神上的寄托;胯部

vt.支撐;支持

sprain

vt.扭傷（關(guān)節(jié)）n.扭傷

ankle n.踝，踝關(guān)節(jié);腳脖子

if you have a sore throat, it may be painful to swallow. A sore throat can be caused by viruses or bacteria.

A burn is an injury to the skin cause by fire or heat. If you get too close to a fire, you will be burned.

An earache is a sharp, dull or burning pain in the ear. Common causes of an earache include an infection, a changing air pressure or water in the ear.

Mountains are landforms higher than 2000 feet or about 600 meters above sea level. Hills are like mountain, but not as tall. Mountains are formed by the forces deep within the earth and are made of many types of rocks

Rivers are stream of water that usually begin at mountains and flow into the sea. Many early cities were built alongside rivers.

Most of the world’s water is in the ocean, which are the large bodies of salt water. The oceans are also an important source of oxygen.

Deserts are areas of land that receive little or no rainfall. The amount of rainfall in some deserts is so low that only a few plants can survive.

A valley is low, relatively flat area between hills and mountains, often with the river running through it. Some valleys are formed by flowing river and others are formed by glaciers.