The Sino-U.S. relations, although they have experienced twists and turns in the past, ______ have moved forward.
He can't go traveling very often as his work __________ almost all his time.
If he fails again, he will __________ us all __________ with him.
We had an anxious couple of weeks, __________ for the results of the experiment.
__________ such heavy pollution already, it may now be too late to clean up the river.
__________ with arms, the soldiers determined to fight against the terrorists.