198. Although Napoleon’s army entered Russia with far more supplies than they had in their previous campaigns, it had provisions for only twenty-four days.
(A) they had in their previous campaigns
(B) their previous campaigns had had
(C) they had for any previous campaign
(D) in their previous campaigns （E）
(E) for any previous campaign
同一army 的两件事情比较，than以后的部分可以省略主语及谓语
AC的谓语动词had补错, 应该是had had.
92. Never before had taxpayers confronted so many changes at once as they had in the Tax Reform Act of 1986.
(A) so many changes at once as they had in
(B) at once as many changes as
(C) at once as many changes that there were with
(D) as many changes at once as they confronted in（D）
(E) so many changes at once that confronted them in
同样一群taxpayers前后发生的事情比较，却在than后补出了主语及谓语. D的confronted补的完全正确, A中的had就是错的。另外，D中代词用了they, 而不是that/those， 因为是自己与自己比。that/those指代同类事物，而不是同一样事物。
结论：同一主语之间（自己与自己）比较，可以省略主语（因为是自己比自己）及谓语，并且只有当主句也用助动词,且比较从句的助动词与主句一致时,才可省略动词只保留助动词. 这里特别要考虑时态问题，如过去完成时与过去时比较，若补出谓语动词，助动词或动词的选择要根据时态来定。若是不省略主语，代词一般用they/it.
以下的两个句子than后面虽然都补了had, 但意思完全不一样。
X had had....than X had... 后面一个had是过去完成时，而非过去时。
X
had...than X had... 后面一个had是过去时, 而非过去完成时。
第二种比较：不同主语之间（X与Y）比较
Innits of the Bering Sea were in isolation from contact with Europeans longer than Aleuts or Inuits of the North Pacific and northern Alaska.
（A） in isolation from contact with Eurpoeans longer than
（B） isolated from contact with Eurpoeans longer than
（C）in isolation from contact with Eurpoeans longer than were
（D） isolated from contact with Eurpoeans longer than were （D）
（E） in isolation and without contact with Eurpoeans longer than
D中were绝对要补，否则产生歧义！
isolated from contact with Eurpoeans longer than from。。。补出from
isolated from contact with Eurpoeans longer than were。。。补出were
两种补出方式（prep. or 动词）产生的意思完全不一样，所以要补出were消除歧义。
结论：不同主语之间的比较可以省略谓语动词，但前提是没有歧义。我看到网上有些说法，认为实意动词不能省略，但系表结构就可以。这种说法很片面，所以我特地举了一个系表结构而不省略的例子。引用一位前辈的话：“。。。ETS如此的reluctant to purport 什么硬性的公理。如何将一个句子表达得准确，简洁，不产生歧义是ETS对句子改错的最高要求。有一些通常的做法，但是决不能生搬硬套。”
同样一群taxpayers前后发生的事情比较，却在than后补出了主语及谓语. D的confronted补的完全正确, A中的had就是错的。另外，D中代词用了they, 而不是that/those， 因为是自己与自己比。that/those指代同类事物，而不是同一样事物。
结论：同一主语之间（自己与自己）比较，可以省略主语（因为是自己比自己）及谓语，并且只有当主句也用助动词,且比较从句的助动词与主句一致时,才可省略动词只保留助动词. 这里特别要考虑时态问题，如过去完成时与过去时比较，若补出谓语动词，助动词或动词的选择要根据时态来定。若是不省略主语，代词一般用they/it.
以下的两个句子than后面虽然都补了had, 但意思完全不一样。
X had had....than X had... 后面一个had是过去完成时，而非过去时。
X
had...than X had... 后面一个had是过去时, 而非过去完成时。
第二种比较：不同主语之间（X与Y）比较
Innits of the Bering Sea were in isolation from contact with Europeans longer than Aleuts or Inuits of the North Pacific and northern Alaska.
（A） in isolation from contact with Eurpoeans longer than
（B） isolated from contact with Eurpoeans longer than
（C）in isolation from contact with Eurpoeans longer than were
（D） isolated from contact with Eurpoeans longer than were （D）
（E） in isolation and without contact with Eurpoeans longer than
D中were绝对要补，否则产生歧义！
isolated from contact with Eurpoeans longer than from。。。补出from
isolated from contact with Eurpoeans longer than were。。。补出were
两种补出方式（prep. or 动词）产生的意思完全不一样，所以要补出were消除歧义。
结论：不同主语之间的比较可以省略谓语动词，但前提是没有歧义。我看到网上有些说法，认为实意动词不能省略，但系表结构就可以。这种说法很片面，所以我特地举了一个系表结构而不省略的例子。引用一位前辈的话：“。。。ETS如此的reluctant to purport 什么硬性的公理。如何将一个句子表达得准确，简洁，不产生歧义是ETS对句子改错的最高要求。有一些通常的做法，但是决不能生搬硬套。”
