按所有、用气体的不同,气体保护电弧焊有()和()等。
参考答案:氩弧焊、二氧化碳气体保护焊
It was not until she had arrived home _____ her appointment with the doctor.
A.did she remember
B.that she remembered
C.when she remembered
D.had she remembered
欲配制1T的N—P2O5—K2O含量为8—10—4的混合肥料,需用硫铵(含N20%)()kg
A.400
B.500
C.66.7
D.33.3