【单选题】由于甲醛的极性较强,在使用气相色谱检测时需要经过 。
【单选题】Which of the word refers to an older, more experienced person who helps you?
【判断题】The connotation of a word is the thing or idea which it refers to.
【简答题】写出下列反应的化学方程式: (1)2002年12月1日,美国哥伦比亚号航天飞机在空中解体,美国政府宣称:“不能私自收藏其碎片,其原因是沾有剧毒的燃料联氨(N 2 H 4 )”.其实在航天飞机碎片与大气层高速摩擦燃烧时,即使沾有联氨也早就燃烧变成了氮气和水.请写出联氨在空气中燃烧的化学方程式:______. (2)氢氧化钠在空气中能吸收水分并能与二氧化碳反应,故应______保存.已知玻璃的主要成分...
【简答题】Leukocyte refers to a white blood cell and erythroblast refers to an immature red blood cell. Please write down the word which refers to an immature white blood cell.
【单选题】Which word refers to a feeling of liking or wanting someone or something more than someone or something else?