高铝质耐火材料的主要成份是()。
A.Al2O3
B.CaO
C.SiO2
D.MgO
参考答案:A
I regret _____ you that my sister regretted _____ you her date. You are not the kind of person she wants. [ ]
A. telling; making
C. to tell; to make
C. telling; to make
D. to tell; making
电液滑阀的自保电磁阀发生动作将阀位保持原位,下列原因哪个不对()
A.反馈信号跟踪失调
B.油压低
C.油温高
D.控制信号低