Exercise might seem like a chore sometimes,     1    (particular) when we get told so often that we should exercise more. But we need to get up and start moving. Many of us spend too much time     2     (stare) at screens. Most teen girls don't meet the standards for physical activity. Getting     3     (scold) about this, though, doesn't really help. And that's too bad, because exercise can be both fun and good for the body and the brain.

Exercise is not only good for your muscles,     4     good for your bones. Getting exercise     5     (help) teens build tough bodies. And teens who exercise more often grow up into adults with much     6     (strong) bones.

Exercise can increase how much oxygen and blood gets to the brain, and even how the brain is structured. Working     7     can produce chemicals in our bodies that might help prevent depression. And a workout after learning something can help us form and keep a great number of     8    (memory).

So maybe it's no surprise     9     so many scientists study exercise. There are some scientists, for instance, who study what makes winning runners so fast.     10    (other) study running lizards and astronauts in space to find out how to keep humans healthy both on and off planet Earth.