was done是什么时态的被动语态

　　The work was done with the minimum amount of effort.

　　做这项工作没费什么劲。

　　The work was done according to her instructions.

　　这项工作是依照她的指示办的。

　　It was done without the principal's authority.

　　做这件事未经校长批准。

　　None of the work was done.

　　那些工作全都未干。

　　What beats me is how it was done so quickly.

　　使我困惑不解的是，这事怎么这么快就完成了。