Definition (分类)
In UK law, a classification of illegal drugs based on their perceived danger and the severity of penalties for their use or sale, with Class A drugs being the most dangerous.
A、B或C级毒品（英国法律中对毒品的分类，依据毒品的危险程度以及使用或贩卖后受到的惩罚程度而定，A级毒品最为危险）
He was prosecuted for possessing a Class A drug, specifically heroin.
他因持有A级毒品，特别是海洛因而被起诉。
Despite the advice from government experts, cannabis was reclassified as a Class B drug.
尽管政府专家提出了建议，大麻仍被重新归类为B级毒品。
Experts were open to the possibility of downgrading ecstasy from a Class A drug to a Class B drug.
专家们对于将摇头丸从A级毒品降级为B级毒品的可能性持开放态度。