Severe steric effects at the reactive carbon would impede the substitution.大的立体效应阻止在碳上的取代.It was intended to impede the apprehension of the person.它旨在妨碍对该人的拘押的.They also impede backmixing of sand.同时也可防止砂子的返混....
It was intended to impede the apprehension of the person.它旨在妨碍对该人的拘押的.They also impede backmixing of sand.同时也可防止砂子的返混.At no time did I make an attempt to impede any investigatory effort.我绝没有试图妨碍过任何调查工作。Severe steric effe...