用所给词的适当形式填空。
The drivers had to drive more slowly and carefully as it got even      (fog).
It was closing time, but the       (interest) tourists were still unwilling to leave.
My mother is        (certain)if she will attend the parents’ meeting tomorrow.
The pair of binoculars will help you see      (clear) when you go birdwatching.
Smiles on the       (swim)faces showed how they enjoyed the race.