铜中加入合金元素可得到较高的强度,能保持纯铜的某些性能,并随着加入元素不同而不同,其中以锌为主要合金元素的铜合金称为()。
A、黄铜;
B、青铜;
C、紫铜;
D、白铜。
参考答案:A
规范语体
A portable dry chemical fire extinguisher discharges by().
A.gravity when the extinguisher is turned upside down
B.pressure from a small CO2 cartridge on the extinguisher
C.air pressure from the hand pump attached to the extinguisher
D.pressure from the reaction when water is mixed with the chemical