因为我对这方面也不太了解,我给我们外教谢了一封信,给他寄了作业,因为前几次都写错了,这次给他寄时,为了希望这次的作业应该

因为我对这方面也不太了解,
我给我们外教谢了一封信,给他寄了作业,因为前几次都写错了,这次给他寄时,为了希望这次的作业应该是正确的,我落款（也就是在名字的上面写了Amen）然后老师给我回信时说where did you get the word Amen from?It is old English and nowadays is mostly found in the Christian Bible.It means something like "we all agree".The word is also found in the ceremonial prayers of the Pharoes (Kings of Egypt) many thousand of years ago.
请问面对老师的这样问,我应如何回答,我是在另外一个外教课上学的这个单词!