65. The changes in the brain seen in marijuana users are similar to those seen in long-term alcohol users. c. first-time crack users.
b.
heroin users.
d. amphetamine users.

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)

Where are the following