54.The main purpose of the passage is to______.求第54题解析,为什么选B不选D ,这两个选项有什么区别The baby monkey is much more developed at brith than the human baby.Almost from the moment it is born,the baby monkey can move around

54.The main purpose of the passage is to______.求第54题解析,为什么选B不选D ,这两个选项有什么区别The baby monkey is much more developed at brith than the human baby.Almost from the moment it is born,the baby monkey can move around
54.The main purpose of the passage is to______.求第54题解析,为什么选B不选D ,这两个选项有什么区别
The baby monkey is much more developed at brith than the human baby.Almost from the moment it is born,the baby monkey can move around and hold tightly to its mother.During the first few days of its life the baby will approach and hold onto almost any large,warm,and soft object in its environment ,particularly if that object also gives it milk.After a week or so ,however,the baby monkey begins to avoid newcomers and focuses its attentions on “mother”-----the real mother or the mother-substitute(母亲代替物).
During the first two weeks of its life warmth is perhaps the most important psychological(心理的)thing that a monkey mother has to give to its baby.The Harlows,a couple who are both psychologists,discovered this fact by offering baby monkeys a choice fo two types of mother-substitutes ----one covered with cloth and one make of bare wire.IF the two artificial mothers were both the same temperature,the little monkeys always preferred the cloth mother.However,if the wire model was heated,while the cloth model was cool,for the first two weeks after brith the baby monkeys picked the warm wire mother-substitutes as their favorites.Thereafter they switched and spent most of their time on the more comfortable cloth mother.
Why is cloth preferable to bare wire?Sometime that the Harlows called contact(接触)comfort seems to be the answer,and a most powerful influence it is.Baby monkeys spend much of their time rubbing against their mothers‟ skins,putting themselves in as close contact with the parent as they can.Whenever the young animal is frightened,disturbed,or annoyed,it typically rushes to its mother and rubs itself against her body.Wire does n‟t “rub”as well as does soft cloth.Prolonged(长时间)”contact comfort” with a cloth mother appears to give the babies confidence and is much more rewarding to them than is either warmth or milk.
According to the Harlows,the basic quality of a baby‟s love for its mother os trust.If the baby is put into an unfamiliar playroom without its mother,the baby ignores the toys no matter how interesting they might be.It screams in terror and curls up into a furry little ball.If its cloth mother is now introduced into the playroom,the baby rushes to it and holds onto it for dear life.After a few minutes of contact comfort,it obviously begins to feel more secure.It then climbs down from the mother-substitute and begins to explore the toys,but often rushes back for a deep embrace (拥抱) as if to make sure that its mother is still there and that all is well.Bit by bit its fears of the new environment are gone and it spends more and more time playing with the toys and less and less time holding onto its”mother”.
54.The main purpose of the passage is to______.A.give the reasons for the experiment B.present the findings of the experiment.C.introduce the method of the experiment D.describe the process of the experiment

54.The main purpose of the passage is to______.求第54题解析,为什么选B不选D ,这两个选项有什么区别The baby monkey is much more developed at brith than the human baby.Almost from the moment it is born,the baby monkey can move around
B项陈述实验发现
D项描述实验步骤
其实没有特别大的不同,陈述实验发现也还是要说点是怎么做实验的,而实验步骤一般就要有首先然后什么的.而且他问的是main purpose,主要目的不是要告诉大家怎么去实验（然后让大家都去实验.）而是向大家介绍他们的发现~

B是讲了实验发现的情况，
D是实验的过程。
也就是说B重点在结果，D在过程。