在锰黄铜ZHMn58-2中加入1%~2%Mn,其目的为()
A.细化晶粒提高强度
B.改善铸造性能和提高强度
C.提高耐磨性
D.提高耐蚀性与耐热性
参考答案:D
We'll fly to the south to see you immediately the tickets become_____. [ ]
A. present
B. available
C. easy
D. convenient
用红外成像仪测量断路器动静触头发热情况,当热点温度大于80℃时,属危急缺陷()