单项选择。
—How did you go to work? —I went .[ ]
A. take a bus
B. by bus
C. by a bus
答案:B
结晶器钢水凝固放出的热量是通过凝固壳→气隙→铜壁→冷却水导出。
社区警务战略的要求是:以社区为依托,立足社区,警民共建。 ( )