专八考试的改错题经常令不少同学头痛。看着一行字愣是不知道错在哪里，有时候甚至还会把对的改错。其实改错题中出现的错误是可以归纳成词组搭配、上下文意思等几大块的。因此，大家在做完了练习后，记得要自己学会总结哦。
For over 900 years, the Tower of London has served as a loyal __1__
palace and fortress. Today, it’s famous for its bloody history and
for being the place where the Crown Jewels are kept.But it has served
for other purposes, too. It has been the royal arsenal, royal mint, __2__
royal observatory or even the royal zoo. The site of the Tower was __3__
originally part of the Roman city of Londinium.
But, in 1066, a foreigner from north west France became King William __4__
of Britain, he ordered that a wooden castle built on the banks of __5__
the river Thames. The purpose of this fortress was to help secure
London, the most important city in his view realm. Ten years later,
William had the fortress rebuild in stone, and created a great __6__
fortified palace with walls three metre thick. Today, this building __7__
is known as the White Tower, and it stands in the centre of a much
larger stone fortress, which was built during later centuries. The
Tower now covers the area of seven hectares, and it stands near the __8__
busy financial district of the capital. But, once inside the high stone
walls, it’s easy to forget the modern world outside and to take a
trip back through history. To help visitors explore, there are special
ceremonial guards, called Yeoman Warders. They are also known as
Beefeaters, and they are the best resource of information about the __9__
Tower’s history. Nearly 40 Yeoman live and work in the Tower.
They are former soldiers who earned the privilege of serving as __10__
Yeoman after long service.
答案及解析:
1.loyal--royal
loyal和royal两个词形似容易混淆，前者是“忠实的”，后者是“皇家的，王室的”。
2.for--/
serve the purpose 的意思是“适用，有……的用途”，不需要介词for。如：
I don’t really think that this piece of furniture serves any useful purpose.
3.or--and
the royal zoo 和前面的the royal arsenal, royal mint, royal observatory都是并列项，所以在最后一项之前应该用and。
4.But^--when;^a--when
原句其实有两个分句， a foreigner from north west France became King William of Britain 和 he ordered that a wooden castle built on the banks of the river Thames,两个分句之间缺少了连词连接。根据逻辑关系，这里应该用表示时间的连接词 when。
5.^built--be
动词order后面的that从句可以是be型虚拟语气，也可以是情态助动词should。所以可以说order that a castle should be built或者order that a castle be bulit。在后一种表达中，表被动的助动词be不能省略。
6.rebuild--rebuilt
这里出现的词组应该是have something done，意思是要求别人做某事。
7.metre--metres
当数词和度量名词之间没有连词符时，名词应该用复数形式。
8.the(area)--an
an area of seven hectares这是一个同位语词组，area前应该用不定冠词。
9.resource--source
resource是“资源”，source是“来源”，所以应该说 a source of information, a source of illness, a source of knowledge等。
10.who^--have
显然earned the privilege of serving as Yeoman这个动作的结果是延续到现在的，应该用现在完成体。