A、 A normal baby responded to the stimuli impassively.
B、 A normal baby's reaction to the sound was phlegmatic.
C、 A group of nurses took care of the blind infants at the medical center.
D、 Some of the blind infants were able to respond to their mothers' voice.

【正确答案】 D

【答案解析】解析：从“But under some special circumstances，some of them were able to react to the sound of their mothers with a smile．”可知有些盲婴在特定环境下会听出母亲的声音并微笑。

A、 The scientists tested them in the medical center.
B、 The blind infants were visited by research workers every two weeks.
C、 The blind infants were made to compare with the normal infants.
D、 Their mothers were invited to tickle them.

【正确答案】 B

【答案解析】解析：研究人员会每两星期对参加测试的婴儿进行调查。

A、 They reacted with smiles to hugging from their mothers.
B、 They were tested for almost a year.
C、 They lacked in feeling to the sound.
D、 They were happy with their families.

【正确答案】 C

【答案解析】解析：盲婴们对任何声音都无动于衷。缺少对声音的感知。

A、 A group of scientists and nurses.
B、 The communities.
C、 The infants' mother.
D、 The local medical center.

【正确答案】 D

【答案解析】解析：从“A special research team organized and dispatched from the local medical center”可推知。

A、 The blind infants' behavior was without feeling or emotion.
B、 The blind infants' behavior was insensible but ardent.
C、 The blind infants' behavior lacked energy and vigor.
D、 The blind infants' behavior took a long time in respond to a stimulus.

【正确答案】 D

【答案解析】解析：由“Usually, their response was very slow and phlegmatic．”可知盲婴对刺激的反应时间较长。