—Would you have told him the answer had it been possible? —I would have, but I ______so busy then.
It is ________ world of wonders, ________ world where anything can happen.
Father ________ for London on business upon my arrival, so I didn’t see him.
The boy’s dream was to have his own laboratory ________ to try out some of his own ideas.
There is a common belief among them ________ rubbish can should be put to good use.
The happy ________ of children playing in the garden disappears, and it is quiet again.