因為had been是過去完成式,時間點是在過去簡單式entered之前,會讓全句的時序顛倒,不符邏輯。
since he entered politics是事件的起點(用了過去簡單式),應該比aggressive的狀況早,所以aggressive要用現在完成式has been aggressive(迄今如此),句子的時序才合理。
(1)For the conj, ever since, used had been; eg:-He had been very aggressive ever since he entered politic.
(2)For the adv, long since, used the present participle; eg:-He entered politics and has been aggressive from himself Mr. Holden since.
eg:-The Mr. Holden has long since been very aggressive.
eg:-He entered politics and has since been very aggressive.