It's best to ask your question to eBay Customer Services on the . com site, as here in the UK there may be different rules. That is, you have to be an established seller with some successful sales under your belt, and attain an Above Average or Top Rates seller status before being able to promote your items.
Just checked, and you are Top rated but perhaps your standard is below that required for promoting, you'll have to ask CS.
Log out of this site, log into www.ebay.com and as CS there, as said it may be a little different for sellers in China.
Contact eBay Customer Services this way, through their help pages.
https://www.ebay.com/help/home
Lines are open between 5 a.m. and 9 p.m. Pacific Time
@lemei06
