【正确答案】 B

【答案解析】[听力原文]
Is language a basic human need without which a child at a critical period of life can be starved and damaged? Judging from the experiment of Frederick in the thirteenth century it may be. Hoping to discover what language a child would speak if he heard no mother tongue, he told the nurses to keep silent. All the infants died before the first year.
Today no such drastic deprivation exists. Nevertheless, some children are still backward in speaking. Most often the reason is that the mother is insensitive to the signals of the infant. There are critical times when children learn more readily. If these sensitive periods are neglected, the ideal time for acquiring skills passes and they might never be learned so easily again.
Linguists suggest that speech milestone is reached in a fixed sequence and at a constant age. At twelve weeks a baby smiles and utters vowel-like sounds; at twelve months he can speak simple words and understand simple commands; at eighteen months he has a vocabulary of three to fifty words. At three he knows about 1,000 words which he can put into sentences, and at four his language differs from that of his parents in style rather than grammar.
Recent evidence suggests that an infant is born with the capacity to speak. What is special about man's brain is the complex system which enables a child to connect the sight and feel. And even more incredible is the young brain's ability to pick out an order in language from the hubbub of sound around him, to analyze, to combine and recombine the parts of a language in novels.
But speech has to be triggered, and this depends on interaction between the mother and child. Insensitivity of the mother dulls the interaction because the child gets discouraged and sends out only the obvious signals. Sensitivity to the child's non-verbal cues is essential to the growth and development of language.

[解析] 本题为细节题。从句子“Judging from the experiment of Frederick in the thirteenth century it may be．Hoping to discover what language a child would speak if he heard no mother tongue，he told the nurses to keep silent．All the infants died before the first year”可知，在实验中，不能听到声音的婴儿最后都死了。因此选B。

【正确答案】 D

【答案解析】[解析] 本题为细节题。从句子“Nevertheless，some children are still backward in speaking．Most often the reason is that the mother is insensitive to the signals of the infant”可知，如果母亲对婴儿发出的信号不敏感的话，婴儿的语言能力就会发展迟缓。因此选D。

【正确答案】 C

【答案解析】[解析] 本题为细节题。从句子“…and at four his language differs from that of his parents in style rather than grammar”可知，四岁大的孩子在语言能力方面语法与父母相近，只是说话方式有所差别。

【正确答案】 A

【答案解析】[解析] 本题为推断题。从句子“But speech has to be triggered，and this depends on interaction between the mother and child．Insensitivity of the mother dulls the interaction because the child gets discouraged and sends out only the obvious signals”可知，母婴之间的语言互动会促进孩子语言能力的发展，反之，则会使孩子的语言能力发展迟缓。