题目内容：

区别主系表与被动语态
The two continents were once joined.

优质解答

被动语态是：主语+be+过去分词+by...The mountain is covered by the big snow.He was injured by a big stone主系表结构：主语+be+过去分词（后面没有by.）The mountain is covered with snow.He was injured in th...