sin(-300°)=sin(360°-300°)=sin60°=32
故选A.
The students are doing the cleaning in their classroom. Some are cleaning the windows and the doors, _______ are sweeping the floor.
A.another
B.the other
C.the others
D.other
提取胡萝卜素和提取玫瑰油时都需要加热,但用萃取法提取胡萝卜素时,采用的是水浴加热,而用水蒸气蒸馏法提取玫瑰油时是直接加热。其原因是[ ]
A.前者需保持恒温,后者不需要恒温
B.前者容易蒸发,后者不容易蒸发
C.胡萝卜素不耐高温,玫瑰油耐高温
D.前者烧瓶里含有机溶剂,易燃易爆,后者是水