Bacille Calmette-Guérin (BCG) is a vaccine for tuberculosis (TB) disease. This vaccine is not widely used in the United States, but it is often given to infants and small children in other countries where TB is common. BCG does not always protect people from getting TB.
Answer: because you think a letter was easiest way to represent the elements. Another way is to use the chemical symbols and it is to allow you to write chemical formulas easily.
Explanation:
A polysaccharide known as glycogen. Glycogen is made of repeating subunits of glucose, which are the quick-energy carbohydrate in animals.
It protects the Earth from becoming over heated, but with pollution, global warming has become more apparent because of the destruction of the ozone layer
