【简答题】(多选)蒸馏操作有加压、减压和常压之分,如下几种物系中,应该采用减压蒸馏分离的有( )*A. 热敏性物系; B. 沸点很低的物系; C. 沸点很高的物系; D. 具有恒沸点的物系。
【简答题】Several days ago, some students from the US visited our school. When we talked, I found __ 1 __ differences in school life between the US and China. For example, each class __ 2 __fifty minutes in the...
【单选题】蒸馏操作有加压、减压和常压之分,如下几种情况中,应该采用加压蒸馏的是()
【多选题】蒸馏操作有加压、减压和常压之分,如下几种物系中,应该采用减压蒸馏分离的有()
【单选题】蒸馏操作有加压、减压和常压之分,如下几种物系中,应该采用加压蒸馏分离的有( )。
C.
乙醛酸法合成香兰素后进行分离得到香兰素(一种食品添加剂)
【单选题】Some ______ visited our school last Wednesday.