More loudly. Most loudly.

Loudlier and loudliest are not correct. Loud, louder, loudest, more loudly -- all ok.

我具体给你解释一下: 词性： loud为形容词，loudly为副词 区别： loud修饰名词，loudly修饰动词 e.g.Her voice is loud. e.g.She is singing loudly. 比较级： loud louder loudest more loudly the most loudly 可以加我微信: 1060802014