I don’t know her address,____ I can’t write to her.

I don't have Mary's address,so I can't write a letter to her I don't know .But you can write to ask her.____.Thank you I want to help her but I don't know what I can do to her I don't know her I want to help her but don't know what I can do or----- to s I don't know what i can do to help her.（改为同义句） I don't--- -- I don't know what happened to her. 请分析这道题：Since I _____ her address,I can not write to her. But （h ） can you?Says her sister you don't know how to write I don't know her.I'll give it to ber.为什么这两句都用her呢?说明 Oh,it's you. I'm sorry I ____ (don't) know you ____ (be) her I don't know her,but I know her name.为什么用her不用his