. Three-fourths of the buildings ______.
In the experiments, the scientists found that water __________ at 100℃.
I am sure your parents are proud __________ you.
—Are you used to __________ in the north with the old couples?—Yes, I am glad to find out that coal is used __________ electricity for home use.
__________ be late for the first class, Bill took a taxi instead of riding to school that morning.
—Bob, are you free at the moment? I have to ask you some questions.— __________.