we need more tents to protect the people in Wenchuan改为被动语态

More tents are needed to protect the people in Wenchuan。 再问： he book was written by her in1990改为主动语态 再答： She wrote the book in 1990。 她1990年写的这本书。 应该是the book,你少打了一个t再问： 为什么 再答： 因为原句是过去式，有明显的过去时间状语，in 1990，所以变成主动语态时也要用过去式，write的过去式是wrote，把原句的her变成主语She，改成主动语态就可以了。