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
