英语、在线等。。。

(A new teaching buliding) was set up (by us) five years ago.
就像中文的“把子句”换为“被字句”，注意划分句子成分即可。加油

We set up a neew teaching buliding five years aog.（主动改为被动）

A new teaching buliding was set up by us five years ago.（主动改成了被动）

A new teaching buliding was set up five years ago by us .（主动改成了被动,我觉得这样好点。）

A new teaching building was set up five years ago.因为此时陈述的主体是教学楼，所以建议by us 可以省略更为通顺。