Which of the following tools is used to model waves?

If the singular term ends in -us, the plural is usually formed by changing the ending to

During weight training, when should you exhale? (hope) a. on the lift b. on the recovery c. before the set d. after the set

What should be changed to make the following sentence true? "the stress model suggests that people with a predisposition for a disorder are more likely to develop the disorder when faced with stress."