帮我把这几个句子改成被动语态.
Someone made it Germany in 1861.
We keep our clavichord in the living room.
My grandfather bought the instrament many years ago.
Recently a visitor damaged it.
Broke two of the strings.
This shocked my father.
Now he doesn't allow us to touch it.
A kind of my father's is repairing it.
然后再帮我解说一下各种时态的被动语态的组成 比如说一般现在时是be+过去分词.