[填空题]
The word horsepower was first used two hundred years ago.
James Watt had made the world’s first{{U}} (11) {{/U}}used steam engine.
He had no way of telling people{{U}} (12) {{/U}}how powerful it was, for
at that time there were no units for measuring power. Watt decided to{{U}}
(13) {{/U}}how much work one{{U}} (14) {{/U}}horse could do in
one minute. He called that unit one horsepower. With this unit he could measure
the work his steam engine could do. He{{U}} (15) {{/U}}that a horse
could lift a 3, 300-potmd weight 10 feet into the air in one minute. His engine
could lift a 3,300-pound weight 100 feet in one minute. Because his engine did
ten times as much work as the horse, Watt called it a ten horsepower
engine.