However, at times this balance in nature is disturbed, _______ a number of possibly unforeseen effects.
Don’t scold him any more. _______, he is only a child.
---The window is dirty.----I know. It ______ for weeks.
He used _______ on the right in China, but he soon got used ______ on the left in England.
The villagers went out to the mountain __________ the missing child.
The room _______ very useful when we had visitors.