石墨层中的碳原子相互连接形成碳环。In graphite sheets, carbon atoms bond together in rings.可分离的碳环化合物环内含七个或七个以下的碳.Isolable carbocyclic compounds contain seven or fewer carbons in the cycle.制取四碳环化合物的特殊方法是在第三十二章中阐述的.Special methods for four ...
药物分为内服药与外用药两类.Medicines are broadly classed as internal or external ones.很多内服药就是催化反应的产物.Many medicines are products of catalysts.这是内服药. 一天四次,每次两片.This is for internal use. Two tablets, four times a day....
During the blitz we spent the night in underground shelters.空袭期间,我们在防空洞过夜.Some of these flood shelters are on raised platforms, which have allowed government helicopters to land amid the continuing floods...其中一些防洪棚搭建在高台上...