Scientists believe nbridge that connected Siberiaand morethan 10，000 yearsago．

Don’t ________ the chance when you can catch it, or you will regret.

The boy doesn’t like ______ when his mother compareshim with the other children in the neighborhood.

Hearing a scream, I rushed downstairs, only ________the hostess lying unconscious on the floor.

“I’m certainly more and more to the conclusion that Iraq has, ____ they maintained（断言）, destroyed almost all of _____ they had in the summer of 1991.” Blix said.