这真的是一个很好的问题.
这两个在例句中都是介词用法.后者比前者多了个out.
through是一个动态介词,常与表示动态的位移动词或(名词)连用,如:walk through the forest.
在时间的数轴上,through表示从一段时间的起点至终点的这个过程.
多了个out的介词throughout ,重点在这个out上.
用汉语来翻译思考,all through the year 和 throughout the year 相当于全年和一年到头的区别吧.
感觉最后一个例句中的have不是位移动词,所以不能用though,
第三个例句,可以用through代替throughout,只是语气不同.
前两个例句不宜用throughout
这是我个人的判断.
最好还是去查一查词典,找出更多的例句.
《牛津双解》
throughout
2 during the whole duration of (sth)
在(某事)的整个期间
Food was scarce throughout the war.
在战争期间食物匮乏.
Throughout his life he had always kept bees.他有生之年一直养蜂.
Throughout their marriage he had only once seen her cry.在他们婚後的日子里,他只看到她哭过一次.
through
2 from the beginning to the end of (sth) 从(某事)的开始至结束; 自始至终;
从头到尾
He will not live through the night,ie He will die before morning.他活不过今天夜里了.
The children are too young to sit through a long concert.这些孩子太小,
音乐会时间长他们就坐不住了.
She nursed me through my long illness.我病了很长时间,她都一直护理著我.
I'm half-way through (reading) his second novel.他写的第二本小说我正看了一半儿.