Throughout the world _______ advance has been made in science and technology is due to education which brings forth knowledge, creation and inventions.
They kept trying _____ they must have known it was hopeless.
There are five pairs, but I'm at a loss which _____ to buy.
He was not an actor, who often appeared on stage, _____ a writer, writing stories.
Please make my excuse at tomorrow's meeting. I've got too much work _____.
I don't know whether to stay in teaching or _____ another job.