力学性能的符号表示ReL(),ReH(),表示Rm(),A表示()。
参考答案:下屈服;上屈服;抗拉强度;延伸率
—What's the noise? It sounds as if it comes from upstairs.
—________. It must be the windowcleaner working next door.[ ]
A. I'm not sure
B. I hope not
C. I'd rather not
D. I don't think so
工业上用来合成氨的原料之一是氢气,有一种来源是取自石油气,有人设计了以下反应途径,假设反应都能进行,其中最合理的是 [ ]
A. C3H8C+H2
B. C3H8C3H6+H2
C. C3H8+H2OCO+H2
D. C3H8+O2→CO2+H2O;H2OO2+H2