【简答题】用官能团鉴定试验区别下列各组化合物: (1)苯乙酮,对甲基苯甲醛和苯乙醛 (2)乙醇,乙醛和丙酮 (3)苄胺,对甲苯胺
【多选题】遵循和掌握体育舞蹈的基本规律是学跳体育舞蹈成败的关键。体育舞蹈的基本规律是()
【判断题】梁的界限破坏是指:在受拉钢筋应力达到屈服强度的同时,受压边缘纤维混凝土应变也同时达到极限压应变。
【判断题】hydraulic piston液压活塞的翻译是否正确?
【简答题】请翻译:Piston fits closely within the engine cylinder or liner and is able to move alternately up and down in the cylinder.
【简答题】请翻译:As the piston starts down on the intake stroke, the intake valve opens and the fuel-air mixture is drawn into the cylinder.