If you can use any letters, it would have to be 2 lower case letters such as tt
        
             
        
        
        
Human activities in the united states such as burning fossil fuels for electricity, heat, and certain transportation.
hope this helps :)
        
             
        
        
        
This process is called melting. When a solid melts, it turns into a liquid. 
 
        
             
        
        
        
The principal function of thyroxine is to stimulate the consumption of  oxygen and thus the metabolism of all cells and tissues. 
Thyroxine is termed T4. It travels through the blood to the target cells and becomes converted to triiodothyronine  or T3. 
T3 is the active form of thyroxine. T3 enters the target cell's nucleus binding to genes responsible  or involved  in the metabolism of sugar in the body. T3 stimulates these genes and in so doing metabolism (conversion of oxygen and calories to energy) is carried out by the cell, which also results in generation of body heat.
 
        
             
        
        
        
The patient could possibly have contracted some sort of foreign disease or might simply have an intolerance to a certain protein such as gluten with celiacs disease.