这个语法点是分词(过去分词、现在分词）作定语和定语从句的考点.
第一句
the book came out last year became a best seller very soon
里出现；两个谓语动词came和became,这是错误所在.句子可改为：
the book that came out last year became a best seller very soon.
第二句
Australia is a big country covers a whole continent
里也出现两个谓语动词is 和cover,句子可改为：
Australia is a big country covering a whole continent.
分词作定语一般可以与定语从句相互转换,所以我只提供部分转换法.