妙辨异同

not only A but also ----B 强调了B
A as well as ----B强调了A

Not only he but also his brothers are coming to see you.不但是他，他弟弟也要来看你。
He as well as his brother is coming to see you.不仅是他弟弟，他也要来看你。

country侧重指“疆土”;
nation侧重指“人民”;
state侧重指“政权，政体”。

He has been to many African countries.----他去过许多非洲国家。
Each nation has a flag of its own.----每个国家都有自己的国旗。
a head of state----国家元首

purpose指追求的目的或达到这一目的的决心、意志、计划或意图等 。
aim作单数指存在心中的目标，比purpose更具体；作复数时指笼统的理想或目标 。

What was the purpose of her visit?----她来访的目的是什么？
What’s your aim in life?----你生活的目标是什么？