【简答题】简述甲醛吸收-副玫瑰苯胺分光光度法测定二氧化硫的原理,测定要点,注意事项。
【单选题】The teacher told his student to make the most of the opportunities ___hand.
【单选题】1,3—戊二烯经臭氧化,在锌存在下水解,可得到哪一种产物?
【单选题】甲醛吸收副玫瑰苯胺分光光度法测定二氧化硫时选择的测定波长为( )nm。
【单选题】The teacher told his students that the earth___________round like a ball.
【单选题】1,3-戊二烯经臭氧化,在锌存在下水解,可得到哪一种产物?