as good as和as well as都是“与……一样好”的意思，但它们的用法不同 as good as　句中动词是系动词（good 是形容词） as well as　修饰的是行为动词（well　是副词） 如 This book is as good as that one.　（is是系动词） 这本书和那本一样好。

Her skirt is as good as mine. (is 是系动词） 她的裙子和我的一样好。This book sells as well as that one.(well 修饰动词sell ) 这本书和那本一样好卖。He speaks English as well as his teacher .　（well修饰动词speak） 他说英语和他老师一样好。