During weight training, when should you exhale?

Catalina ate a candy bar and then went on a fast-moving ride in an amusement park. she was sick to her stomach after the ride and now, catalina cannot eat candy bars, because they make her nauseous. in this learned association, the candy bar serves as a(n) to catalina.

The outermost layer of your teeth is called the enamel and is made of?

Can someone give me one specific health problem, and explain it. !