The eyes are one of the most expressive instruments of body language. Keith，seventeen，from Montclair New Jersey，learned the hard way about one 1 the eyes can make .“I had a teacher who graded heavily on classroom discussion, Keith says. “He seemed to have a strong ability to know just when I didn’t have the 2 . I couldn’t figure out how he could be so _3_.Then it dawned on（为……所明白）me. 4 I didn’t know the answer，I would avoid looking at him. When I did know what to say，I always glanced(扫视)straight back at him. From that moment on，I 5 myself to look at him in the eye, 6 I knew the work or not. That trick has saved me a lot of trouble.”
