If what you are teaching doesn’t _____ to your students, your students will gradually lose interest in it.
With temperature ________ so rapidly, we could not go with the experiment.
How did it ________ that the ancient building was burnt down in an hour?
—An ant has two stomachs—one for itself, one for others. —Really? Quite interesting. I ________ anything about it.
Noise is unpleasant, ________ when you are trying to sleep.
—Was ________ problem solved? —We were trying to think of ________ way out, but it was difficult to find one.