請問這句附加問句要肯定還是否定？ This thing is unfair, ?要填isn't it 還是而is it ??

This thing is unfair, isn't it? (O)

一般來說，附加問句是用肯定的去接否定的直述句，用否定的去接肯定的直述句：
You love Susie, don't you?
She can't dance, can she?
附加問句語調上揚時，講話的人對自己的話沒有信心，想對方確認；附加問句語下降時，講話的人對自己的話有絕對的信心，要對方認同。

也可在肯定句後加上肯定的附加問句，用來向對方確認。
His father is ill, is he. (他的父親生病了，對吧？）

以上說明及例句請參見pp.36-37綿貫陽著《新觀念英文法》眾文圖書公司2013年出版

所以以下兩種方式都正確，因為主句是肯定句，附加問句可以否定，也可以肯定：
This thing is unfair, isn't it? ...不對嗎？
This thing is unfair, is it? ...對吧？

This thing is fair, isn't it?（肯定＋否定）
This thing is fair, is it?（肯定＋肯定）主句是肯定，可接肯定的附加問句。
This thing isn't fair, is it?（否定＋肯定）。

Michael Swan著《牛津英語用法指南》第二版p.700
「同向」疑問尾句
在肯定句後面常用肯定的疑問尾句。這些尾句用來對前面所說的事的反應，如興趣、驚奇、關心、或其它反應，如：
So you are getting married, are you? How nice!
So she thinks she's going to become a doctor, does she? Well, well.
You think you're funny, do you?

以下是用尾句來確定是否正確：
Your mother's at home, is she?
This is the last bus, is it?
You can eat shellfish, can you?

在「英國英語」中，偶爾會聽到否定句後用「同向」的否定附加尾句，這聽起來往往咄咄逼人：
I see. You don't like my cooking, don't you?
=我明白了。你不喜歡吃我做的菜，是不是？

看來有規則，就有例外。依《牛津英語用法指南》，否定＋否定，也是正確的。

"This thing is unfair." (1) To change into positive and interrogative sentence: Does this thing unfair is it? (2)To change into negative and interrogative sentence: Does this thing unfair isn't it ? Yip