FeiFei-76请教

melontree

76. Learning how to build a nest plays an important part in the breeding success of birds. For example, Dr. Snow has recorded the success of a number of blackbirds in several successive years. He finds that birds nesting for the first time are less successful in breeding than are older birds, and also less successful than they themselves are a year later. This cannot be a mere matter of size and strength, since blackbirds, like the great majority of birds, are fully grown when they leave the nest. It is difficult to avoid the conclusion that they benefit by their nesting experience.

Which one of the following, if true, would most weaken the argument?

(A) Blackbirds build better nests than other birds.

(B) The capacity of blackbirds to lay viable eggs increase with each successive trial during the first few years of reproduction.

(C) The breeding success of birds nesting for the second time is greater than that of birds nesting for the first time.

(D) Smaller and weaker blackbirds breed just as successfully as bigger and stronger blackbirds.

(E) Up to 25 percent of all birds are killed by predators before they start to nest.
  
问问为什么选项是B?

jnlvo

fficeffice" />    思路：结论：How    to    build    a    nest    is    very    important.第一句话。论据：birds    nesting    ,不如老bird    success,    also    less    than    。。。其实就一句话，新birds没用经验nesting,所以生育成功率低。
削弱方向：1.断桥，论据与结论无关，即新birds    nesting。。    推不出how    to    build    a    nest    plays    an    important    part    in    the    breeding    success    of    birds.
                                        2.他因：有其他的原因可以解释论据。
                                        3．驳斥论据的有效性；

A:无关，比较点不对，和其他bird无关
B，他因，success    是与capacity    有关。
c.无关，陷阱，把论据重新说呢一遍。The    breeding    success    of    birds    nesting    for    the    second    time    is    greater    than    that    of    birds    nesting    for    the    first    time.=    He    finds    that    birds    nesting    for    the    first    time    are    less    successful    in    breeding    than    are    older    birds,    and    also    less    successful    than    they    themselves    are    a    year    later.
D:无关，文中没有比较smaller    ,weaker。Smaller,    weaker    birds    完全有可能知道    how    to    build    a    nest    .
E:无关，birds被杀和breeding    success    of    birds    无关，如果是出生（breeding）的birds    被杀就有关了。
评论：排除法是最有效的，因为不正确选项简单。而正确选项的推理过程有点扰。

melontree

多谢多谢!!!