At times, worrying is a normal __________ to a difficult event or situation—a loved one being __________ in an accident, for example.
He ___ Beijing for a long time.
Our teacher taught us that water ___ at zero degree centigtade.
When I was a little child, Father told me the earth ___ round then sun.
The boy wrote_____last week.
There are ten___teachers and two hundred___students in the school.