English term (edited): active buyers and sellers

Hi Xuling!

I´d like to share my humble opinion.
In the first example given above, I would translate it as ¨活跃的买家和卖家¨ or ¨活跃的交易用户¨which means that they frequently log onto the eBay website/app and conduct (a great many) transactions.

Normally, these ¨active buyers and sellers have already validated their information when they registered. Thus, they are verified users (已通过验证的用户/有效用户).¨
To put it simply, “活跃的买家和卖家” 通常已经表明 他们是 “有效用户了”。简而言之，“活跃的买家和卖家” 具体指的是 eBay的有效用户中经常做交易的那一部分人。