同级比较结构1.原级比较结构出现含有“as…as…”的结构中。该状语从句修饰比较副词as，状语从句的结构和主干完全相同。和一般比较结构类似，该句话也可以省略，只是比较的对象要保持一致。He is as handsome as David. 2. as从句和than从句都可以采用倒装尤其是as或than从句之后有定语从句时，为了方便就近修饰，可采用倒装。He is as prudent as David is, who is one of my favorite friends.改为: He is as prudent as is David, who is one of my favorite friends.He is more prudent than David is, who is one of my favorite friends. 改为: He is more prudent than is David, who is one of my favorite friends. 3 .“as…as…”可以用于肯定或否定句，“so…as…”则只能用于否定句 He is as polite as David. He is not as polite as David. He is not so polite as David. 他不像大卫那么有礼貌。 比较级结构的一些特殊用法 1.两个形容词也可以相互比较“more…than…”结构中，若为两个形容词相互比较，则这两个形容词一律使用原级。He is more good than bad. =He is not so bad as good. =He is good rather than bad. 2.倍数词造句法倍数词造句法一共有四种： David is three times as heavy as that baby.大卫的体重是那个小孩的三倍。David is more than three timesas heavy as that baby.大卫的体重是那个小孩的三倍还不止。David is three times that baby’s weight. =David is three times as heavy as that baby.大卫的体重是那个小孩的三倍。David is more than three times that baby’s weight. =David is more than three times as heavy as that baby.大卫的体重是那个小孩的三倍还不止。课堂练习Judging from the width and depth of the channels, the flow rates must have been truly enormous ― perhaps as much as a hundred times greater than the 105 tons per second carried by the great Amazon river. 3.not so much…as…与其说是……倒不如说是……这个结构后面可以跟下面几种对应的形式，但由于much不能修饰形容词和副词的原形，故当跟的对象是形容词或副词时，much可以省略。Be not so much + adj/adv/n/prep/to do/v + as + adj/adv/n/prep/to do/vShe is not so (much) beautifulascharming.（much省略掉）与其说她美丽，不如说她迷人。David is not so mucha writerasa scholar.与其说大卫是个作家，不如说他是个学者。 4. no more …than…/no less…than…此类结构一共有4种：1） no more…than…(不是……正如……) = not any more…than…He can not dance, just as I can not dance. =He can not dance any more than I (can). =He can no more dance than I (can).他不会跳舞，正如我也不会跳舞一样。课堂练习They are no more valid today than they were in those years. 2） no less…than…(和……一样) = as…as…He is no less good at Math than I (am). =He is as good at Math as I.他和我一样精通数学。 3） not more…than…(没有比……更多) = at best as…as…(*多和……一样……)She is not more beautiful than Mary. = She is at best as beautiful as Mary.她不比Mary美丽 = 她*多和Mary一样美丽。 4） not less…than…(没有比……更少)= at least as…as…(至少和……一样……)She is not less beautiful than Mary. = She is at least as beautiful as Mary.她至少和Mary一样美丽。 5.at most/at best1) at most/no more than/not more than + 次数*多He is at most eight years old. =He is no more than eight years old. =He is not more than eight years old. 他*多8岁。 2) at best/nothing but充其量/只不过是This is at best a second-rate University. =This is nothing but a second-rate University. 这只不过是个二流的大学。课堂练习Though ancient humans might have mastered prehistoric crampons, mastodons almost certainly did not, and finding food and shelter under those circumstances would have been difficult at best.
