The room is dusty._______________.

Scientists are convinced ___ the positive effect of laughter ____ physical and mental health.

Man’s shopping can be and often is completed in five minutes，which is less than a quanrter ________。

didn’t you try to finish thecomposition— I tried to , butI could, the bell rang announcing the end of the examination time

It is not who is right but what is right is of importance.[ ]