徹底說再見，英語是：Say goodbye thoroughly.

詳細解釋：

say 英[seɪ] 美[se]

vi. 說， 講; 表明，宣稱; 假設; 約莫;

vt. 表明; 念; 說明; 比方說;

n. 發言權; 說話; 要說的話; 發言權;

[例句]I would just like to say that this is the most hypocritical thing I have ever heard in my life

我只想說這是我這輩子聽說過的最虛偽的事情。

goodbye 英[ˌgʊdˈbaɪ] 美[ˌɡʊd"baɪ]

n. 再見;

[例句]He said his goodbyes knowing that a long time would pass before he would see his child again

他道了別，知道要過很久才能再見到他的孩子。

thoroughly 英[ˈθʌrəli] 美[ˈθɜ:rəli]

adv. 徹底地; 認真仔細地; 完全地; 非常;

[例句]He was surprised to find his room thoroughly cleaned and everything arranged in perfect order.

他驚奇地發現房間被徹底打掃了，一切都佈置得井井有條。