Why do you think it would be important to know that both
sides of the heart receive
blood at the same time. Please use your own words

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)

Apenis is also called phallus

You can always get a sexually transmitted disease. always ask for consent before doing anything..because you never know if your bf or gf has an std!