"错选A
A\B which指代conquest，其他国王不能重复 丹麦征服英国的这个历史事件。重复的只能是成就
C选项 an achievement that kings attempted to repeat but kings were not successful at it. it指代achievement。但是定语从句就是来修饰achievement的，不能在定语从句中再用代词指代achievement
I was reading a book that had just been printed and that no one else had read
--> correct. note that the whole modifier describes ""book"".

I was reading a book that had just been printed and that no one else had read it
--> incorrect. the ""it"" here is stranded, because the modifier is already trying to describe ""book"".

I was reading a book that had just been printed; no one else had read it
--> correct. now that the second part is an entirely different clause (separated by the semicolon), it's appropriate to use ""it"" to refer to the noun in the first clause.
D 尝试复制和没有成功之间应该是转折关系（but）而不是解释说明关系（that）。（并且，that was not successful的主语也不正确）

E 省略other Scandinavian kings attempted to repeat later without success."

(D)an achievement attempted later in the century by other Scandinavian kings that was not successful

This choice incorrectly says that the achievement was unsuccessful; but, the logical and intended meaning is that the attempt was not successful.

请问C选项的it为什么不能理解为指代的是achievement呢？
个人感觉C选项的it有赘余嫌疑。。。

选项E（√）
The Scandinavian assault on Western Europe culminated in the early eleventh century with the Danish conquest of the English kingdom,
an 【achievement】 that other Scandinavian kings attempted to 【repeat】 later in the century, but (other Scandinavian kings attempted to repeat later 被省略) without success.
斯堪的纳维亚对西欧的进攻在 11 世纪初 随着丹麦征服英国王国 而达到高潮，
其他斯堪的纳维亚国王试图在本世纪后期【重复】这一【成就】，但（其他斯堪的纳维亚国王试图在以后重复）没有成功。

A选项（×）：【the English kingdom（×）】, which other Scandinavian kings attempted to 【repeat】, unsuccessfully, later in the same century
能被重复的（repeat的宾语）只能是过去的成就achievement，而不能是“英国he English kingdom”。

C选项（×）：an achievement that other Scandinavian kings attempted later in the century to repeat, but were not successful at 【it（×）】
根据语义，were not successful at的对象应该是整个复制的行为，而不是某一个单数名词。
it只能指代单数名词，不能指代句子（整个复制的行为，即，other Scandinavian kings attempted later in the century to repeat）。

D选项（×）：an achievement attempted later in the century by other Scandinavian kings 【that （×）】was not successful
尝试复制和没有成功之间的关系是转折（but），而不是解释说明（that）。
并且，that was not successful的主语（×）

C错误：在逻辑上，were not successful at的对象应该是整个复制的行为，而不是某一个单数名词。
E：but without success是一个省略句，还原为正常的句子为
other Scandinavian kings attempted to repeat later without success.

(C)(D)(E)用了同位语，定语从句that other Scandinavian kings attempted later in the century to repeat的先行词为an achievement，也充当repeat的宾语。

C选项：代词it的指代对象只能是单数名词，不能指代句子。在逻辑上，were not successful at的对象应该是整个复制的行为，而不是某一个单数名词。
other Scandinavian kings attempted later in the century to repeat, but were not successful at it是an achievement的定语从句。不能用定语从句的某个成分去指代先行词啊（那样整个逻辑就乱了，本来定语从句就是修饰语，在地位上低了先行词一头，不能在定语从句里用一个代词去指整个先行词嘛）

E选项：Correct. 本选项在语法和逻辑上均是正确的。but without success是一个省略句，还原为正常的句子为
other Scandinavian kings attempted to repeat later without success. (省略！)

an achievement attempted later in the century by other Scandinavian kings that was not successful 语义是说 an achievement was not successful--即前半句的achievement

an achievement that other Scandinavian kings attempted to repeat later in the century, but without success
but 作为连词，后面加介词短语，整个句子被省略了
应该是repeat一种模式，而不是重复上一次特定的征服

an achievement that other Scandinavian kings attempted later in the century to repeat, but were not successful at it
-> repeat -> it . repeat can not be taken as a noun

an achievement attempted later in the century by other Scandinavian kings that was not successful
was -> need a noun ahead. but attempted cannot be the noun

attempt to repeat，理解成attempt是助动词行不行

错选A
A\B which指代conquest，其他国王不能重复 丹麦征服英国的这个历史事件。
C选项 an achievement that kings attempted to repeat but kings were not successful at it. it指代achievement。从语意上，此处应该是定语从句。如果是同位语也不会能出现 achievement（it）去解释achievement.
E 省略other Scandinavian kings attempted to repeat later without success.

it 指代？ 多余？
同位语从句

另外，which引导的定语从句是限制修饰先行词的内容，而同位语是解释，可以和先行词划等号。

As what Ron has said, "which" must modify the NOUN precedes the comma. If the NOUN is followed by a prep. modifier, it is also fine.
However, "which" cannot modify a sentence.

c, it指代名词achievement，而不能指代repeat the achievement

D，attempt/try sth，试一下某物，如try this food, 尝尝这道菜；try/attempt to do sth，设法做某事，尽力做某事

AB选项which指代错误，排除
C选项：it只能指代单数名词，不能指代句子，但是这边应该指代整个repeat的行为❌
D选项：that指代不明❌
E选项：✅but without success是一个省略句，还原为正常的句子为
other Scandinavian kings attempted to repeat later without success.

正如my swimming yesterday不能被另一个人重复，他只能重复游泳这个概念。

A/B，which指代conquest，丹麦对英格兰的征服这个历史事件是不能被其他国王repeat的，能repeat的是把这件事抽象化成一个achievement，repeat一个类似的成就。
C，an achievement that other Scandinavian kings were not successful at it . 这里的that只能只能引导定语从句，it多余；不能做an achievement的同位语解释说明achievement的内容，一是语意上“其他国外在这件事上不成功”并不是achievement的内容，而是它的一个属性，用定语从句，二是同位语里也不能出现it，不能自己同为自己。
E, kings attempted to repeat the achievement, but without success. but是连词，接介宾短语构成的状语，没有并列对象，属于an exceptional use。

but的用法：
可以做并列连词，表转折；

可以做介词，表示“除了”，如：
Everyone but Jim went to school.
I came last but one in the race. 我赛跑得了倒数第二名。

可以做副词，等同于only，如：
There were a lot of famous people there: Tom Hanks and Julia Roberts, to name but two.

but的其他特殊用法如：
The grasses develop an extensive root system, but without growing too tall.
I had no choice but to sign the contract. 我别无选择，只好签了合同。
He would have played but for a knee injury. 他要不是膝部有伤的话，就上场了