If I were you, I would state that my residential address is where I am living in China. You can include a letter attached to that form, explaining the situation in more detail, though I don't think it is necessary.
another question.. my wifes hokou says she is living at her sisters appartment, but she is living at a different appartment with me. what address should I put on the application?
State the address she is actually living at with you. The hukou being a different address is a problem that should be addressed in the application. So get proof that she is not living with her sister any more, and is living with you at ____. Things like: an affidavit from the sister stating your wife is not living there now; an affidavit from your current landlord stating that the two of you are living there; a copy of the lease - if both your names are on it, great, but if only her name is on it, at least it shows she is not living with her sister anymore.
I suggest you also get letters of support from relatives and friends, stating that your relationship is genuine. In these letters they can include that they know you and your wife are living together at ____.
I only know things about immigration because when my own husband applied, and was rejected, I started to research immigration. One thing that taught me a lot was reading about immigration appeal cases on Reflex and CanLii:
http://www.irb-cisr.gc.ca:8080/ReFlex/Issue_Index.aspxhttp://www.iijcan.org/en/ca/irb/index.htmlI definitely wish I knew about this forum before I applied!