In the city squares the neon lights flashed in turn.在城市广场上，霓虹灯依次闪烁。Theory is based on practice and in turn serves practice.理论的基础是实践,反过来理论又为实践服务.They answered the teacher's questions in turn.他们依次回答了老师的问题....
R ” 是取化基,如乙氧基 、 甲氧基及它们的环氧和烷氧同系物或卤基.R " is a replaceable function , e . g . acetoxy, methoxy, their acyloxy and alkoxy homologs or halo.蒸馏得质量分数高于98%的邻乙氧基苯甲酸,收率为92%.Distillation gave o ethoxybenzoic acid with 98 % of the p...