Why does my brother sleep until 12pm and stays up till 12am

Because to balance the sleep

Immunization is the introduction of a foreign substance to provoke  the immune response system.  immunizations are the same as vaccinations. it introduces foreign (but dead/ weakened) illnesses to train the body to fight against them. specific viruses and bacteria have specific antigens, antigens act sort of like name tags. these name tags the immune system recognize what's dangerous to the body and what's safe. 

Which of the following statements are false: "an unplanned pregnancy can  decrease the risk of getting pregnant again.  answer should be bold it in.hope it you.-charlie!