It can be inferred from the last paragraph that Christopher______.

In a quiet，darkened lecture room，you begin a frustrating fight against fatigue. The overhead projector hums，and you cannot concentrate on the slides. You stop absorbing information and become absent-minded. The professor lost you a long time ago. You are bored.

It can be concluded from Para. 2 that______.

Researchers hold that boredom results from______.

Improvement of people's ability to focus may______.

The passage mainly involves______.