1.第一是章振邦语法书上的比较结构课后习题有的困惑：
He admits that he is more apprehensive for his own safety than that ofhis family. 这句话为何是不对的，还需要在than 与that之间补上for呢
Forrester has never done any campaigning and never will. 这句话是正确的吗？
Advice is like snow：the softer it falls，the longer it will dwell upon，and the deeper it will besinking into ,the mind. 这句话为什么要将will be thinking into改为will sink into呢？
2.在than的比较状语从句中愈加困惑，弄不了解到底何时该省略什么成分？
21年专四考试试题：
Data has shown that more Hispanic and black students are majoring incomputer science and engineering than _______.
A. those are being hired
B. are being hired
C. being hired
D. hired
此处是怎么样选出hired的，而不可以选C呢（假如理解为主语相同，表语相同）
GMAT考试试题
Analysts blamed May's sluggish retail sales on unexciting merchandiseas well as the weather, colder and wetter than was usual in some regions, whichslowed sales of barbecue grills and lawn furniture
colder and wetter than was usual in some regions, which slowed
which was colder and wetter than usual in some regions, slowing
since it was colder and wetter than usually in some regions, whichslowed
看到分析是说：答案。与[例三]一样存在形容词usual，补全主系：
The weather was colder and wetter than usual weather was in someregions.
中which用错误。than结构存在作状语的副词usually，要补全主系结构。但比较关系是正确的，补全后：
It was colder and wetter than it usually was in some regions.
看到这里彻底困惑了，到底何时该省略什么成分呢？怎么分辨他的省略是正确的呢？
1 He admits that he is more apprehensive for his own safety than that of his family.
这个比较分句补全后为：
He admits that he is more apprehensive for his own safety than he is for that of his family.
than分句的主语和谓语动词he is与主句相同，可以省略。作表语的形容词为比较对应项是需要省略的，但表语形容词的补足语与主句不同，需要保留。形容词的补足语为for介词短语，所以for不可以省略。
Forrester has never done any campaigning and never will. 这句话没问题。will后省略了do it.此时will需要重读，中位状语never需要坐落于重读的操作词之前。
Advice is like snow：the softer it falls，the longer it will dwell upon，and the deeper it will be sinking into the mind. 这是作者用雪渗入土壤比喻建议让人同意，所以用了sink into the mind. thinking into the mind 本身就是逻辑混乱的。
2 Data has shown that more Hispanic and black students are majoring in computer science and engineering than _______.
A. those are being hired
B. are being hired
C. being hired
D. hired
本句主句的比较短语为more Hispanic and black students，其对应项在从句中做主语是需要省略的，所以than后应该为谓语动词。由此排除A、C二项。虽然比较分句谓语为被动语态时有时可以省略助动词be，但这与谓语动词有关，如plan，expect，think，admit，intend，realize, predict等的被动语态常省略be而只保留过去分词。但hire不是此类动词，其被动语态不能省略be的。所以排除D，B为正确答案。
GMAT考试试题
Analysts blamed May's sluggish retail sales on unexciting merchandise as well as the weather, colder and wetter than was usual in some regions, which slowed sales of barbecue grills and lawn furniture
colder and wetter than was usual in some regions, which slowed
which was colder and wetter than usual in some regions, slowing
since it was colder and wetter than usually in some regions, which slowed
这个题其实是考察than usual的意思和使用方法。than usual目前基本成了习语，但其实它是比较分句的简略。than usual=than is usual. 省略的是一般目前时的is，由于usual有下面使用方法：It is usual for somebody to do something. it为形式主语，不定式复合结构为外置主语（真的主语）。该句意思是这个5月份的天气比一般5月份的天气冷且多雨。比较的是一般5月份，than从句省略的是一般目前时系表结构的系词is，而不是was。所than usual一般省略系词be，但补上be不算错，但不可以是was。A项的错误在于was，C项的错误在于since这个状语从句修饰哪个说不了解，且同样存在was的时态错误。正确答案为B，补全的than分句为：
which was colder and wetter than it is usual for it to be in some regions, slowing
不定式复合结构中的to be的表语为比较对应项，需要省略，不可补全。to be的逻辑主语for it指代the weather.然后这个比较分句可以省略，第一步省略形式主语it 和外置的不定式复合结构，得到：
which was colder and wetter than is usual in some regions, slowing...
在than is usual 这个系表结构中，当表语为某些形容词时，系词be可以进一步省略，比如necessary，possible，normal，usual等。于是进一步省略is，则得到：
which was colder and wetter than usual in some regions, slowing...