被动语态一定要有介词吗

Question

His plays are known all over the world这是被动语句,那介词在哪?还有His plays are turned into wonderful films呢??

Answer 1

其实没有必要这么较真，被动语态表示被动，从理论上来说是“被..."肯定要有介词，但是被的对象不明确的话就没有必要写出来。His plays are known all over the world。=His plays are known by the world。
His plays are turned into wonderful films.这句话”被...”省略掉了，完整应该是：His plays are turned into wonderful film by sb.

Answer 2

不一定要有介词。
His plays are known all over the world.
他的剧作闻名于世界。
His plays are turned into wonderful films.
他的剧作变成了电影。

Answer 3

本来应该是
his plays are known by everyone all over the world .
his plays are turned into wonderful films by some directors

其中的by 就是介词

这里的by someone 很多情况下可以省略

所以不一定要介词

Answer 4

over是该句的介词
into是借此
被动语态不一定有介词，例如i was hurt

Answer 5

被动语态不是一定要有介词的