下列叙述正确的是()
A. 所有的物质都有旋光性
B. 旋光性是由分子之间的相互作用导致的,与单个分子的性质无直接关系
C. 将两种比旋光度相反的物质等量混合,混合物的溶液不旋光
D. 由手性分子组成的纯物质的溶液一定有旋光性
They answered with ___ (assure) that it was against the rules.
He glanced briefly towards her but there was no sign of _________( recognize).
Vitamins are _________ (essentially) to the proper nourishment of the body.