+H2C=CH2 →一定条件
+2H2C=CH2 →一定条件
丙烯是三大合成材料的基本原料,可用于合成应用广泛的DAP树脂单体和双酚等有机物,具有重要的工业用途.
First-class players of football must have excellent ball control, but it is not just _____ they do with their feet _____ counts.
党的基本路线的核心内容是( )
真的猛士,____ ,敢于正视淋漓的鲜血。(鲁迅《记念刘和珍君》)