蛋白泡沫灭火剂主要用于扑救B类火灾，也适用于C类火灾，但有限制。
参考答案：错
—The school has a long history.
—It ________ 100 years ago. [ ]
A. built
B. has built
C. builds
D. was built
力偶不可以用一个合力来平衡。
