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virus


a type of germ that can cause a disease

 

stress


worry, strain, or pressure

 

immune system


the system that protects a body from germs and disease

 

certified


officially allowed to do something because you have had
the necessary training

 

biology


the study of living things

 

dissolves


breaks apart or melts when mixed with liquid

 

cavity


a hole

 

radar


a device that sends out radio waves to locate something

 

geologists


scientists who study the Earth by examining rocks

 

erosion


the process of being worn away