各位好，請教一下
在朗文辭典看這樣的例句：https://www.ldoceonline.com/dictionary/back
She was the one who had fired him from his first job back in South Africa.
為何這句子後面要用過去完成式had fired呢？應該也可以只用過去式吧？如：
She was the one who fired him from his first job back in South Africa
過去式就可以表達了，想不出要用過去完成式的理由。後來我試著想像一個語境：
(She told me that) She was the one who had fired him from his first job back
in South Africa.
這樣對我來說，用過去完成式就合理了。
「她告訴我」發生在過去，而「她在他第一份工作時開除他」發生在「她告訴我」之前，
也就是「過去的過去」，因此用過去完成式。
不曉得我用這個方式理解可以嗎？有張貼在英語討論區https://goo.gl/vHzdHK，
不過還沒有人回應，那邊如有回應會再貼回來和大家討論。謝謝！