Seeing a large crowd at the street corner,I became aware of________unusual happening.
The news that volunteer workers will go to homes for the aged ______now.
Believe it or not, crying is a way you can imagine ______ pressure.
__________ the students who have taken part in the sports game is unknown.
_______, the more exercise you do, the richer your knowledge will be.
His mother happened _______ when his program was shown on Channel Young.