1.   These glasses keep slipping down my nose.

2.   His wraparound glasses keep out wind and dust as well as ultraviolet and some infrared rays.

3.   In France glass has kept its connotations of modernity.

4.   Nurses change his sheets four times a day, he said, because glass keeps coming out of him.

5.   The extra-thick glass no doubt kept out all but the loudest of exterior sounds.

6.   The only thing that worries me is his glasses keep fogging up.

7.   Greenhouse gases tend to trap heat, the way glass keeps heat in a greenhouse.