No caffein,there is a factor that must not be changed when conducting an experiment,known as controlled variable
A vaccine works by training the immune system to recognize and combat pathogens, either viruses or bacteria.
Answer:
A friend is a person whom one knows and with whom one has a bond of mutual affection, typically exclusive of sexual or family relations.
Humans require food to continue to function, we overeat, and undereat. The more food we have the better we wil live
