He posted the letter two hours ago.改为被动语态

问题描述:

He posted the letter two hours ago.改为被动语态

the letter was posted by him two hours ago.

The letter was posted by him two hours ago.
被动语态中,原句主语与宾语替换位置;而原句中谓语为过去时,letter又是单数,所以用was