The students were ____ over the ____ problem, listening to the teacher with a ____ expression on their faces.
Please call my secretary to arrange a meeting this afternoon, or ________ it is convenient to you.
She usually keeps her valuables, such as jewels and money, ________ she believes secure.
How can they expect to learn anything ________ they never listen?
—I wonder how much you charge for your services. —The first two are free ________ the third costs $30.
—I think George doesn't really care for TV plays. —Right, ________he still watches the program.