此句能用both...and吗?

An Englishman can usually find someone in almost any part of the world who is able to talk to him in either English or French.

此句中的either English or French.可否改成both English and French吗?
可以,为什么?
不可以,又为什么呢?

此句能用both...and吗? both of 和 both ... AND....有什么区别吗? My parents and I are both at home. 次句为什么用both? He has two sons, both of whom are workers. 此句中whom可以换成them吗？ both……and both....and造句 both与both......and......的区别 Both his father and mother is a teacher .这句英语对吗? Both he and I____ teachers . Both you and I be ``!