总体参数估计有()和()两种方法
参考答案:点估计;区间估计
---I wanted to be a soldier when I was a little boy.
--- .
A.So I was
B.So was I
C.So I did
D.So did I
CO2气体保护焊所用的CO2是还原性气体,对焊缝无氧化作用。