You'd better make a mark _____ you have any questions.
—Look at these black clouds. It ______ soon.—Sure. If only we ______ out.
We thought the examination would be difficult, but it ______ easy.
He has some ______ with English, but he doesn't speak it fluently.
His business was very successful,but it was at the ______ of his family life.
As the Red Cross ______ for help for the earthquake victims, much money has been raised.