A blind baby is doubly handicapped. Not only is it unable to see, but because it cannot receive the visual stimulus from its environment that a sighted child does, it is likely to be slow in intellectual development. Now the ten-month old son of Dr. and Mrs. Dennis Daughters is the subject of an unusual psychological experiment designed to prevent a lag in the learning process. With the aid of a sonar-type electronic device that he wears on his head, infant Dennis is learning to identify the people and objects in the world around him by means of echoes. The device is a refinement of the "Sonicguide", an instrument produced by Telesensory Systems, Inc., of Palo Alto, Calif., and used by blind adults in addition to a sane or guide dog. As adapted for Dennis, it consists of a battery-powered system about the size of a half dollar that is on a headgear. A transmitter emits an ultrasonic pulse that creates an 80 degree cone of sound at 6 feet. Echoes from objects within the cone are perceived as sounds that vary in pitch and volume with the size and distance of the object. The closer an object is, the lower the pitch, and the larger the object, the louder the signal. Hard surfaces produce a sharp ping, while soft ones send back signals with a slightly fuzzy quality. An object slightly to the right of Dennis sends back a louder sound to his right ear than to the left. Thus, by simply moving his head right and left and up and down, he can not only locate an object but also get some notion of its shape and size, thanks to the varying qualities of sounds reaching his ears as the cone of ultrasound passes its edges. Dennis likes to use the device to play a kind of peek-a-boo with his mother. Standing on her knee and facing her directly, he receives a strong signal in both ears. By turning his head away, he makes her seem to disappear. From the first time he wore it," says Mrs. Daughters, "it was like a light going on in his head." What remains to be determined is how well the device will help Dennis cope with his surroundings as he begins to walk and venture further into his environment. Meanwhile, Telesensory, Inc. is working on the development of sonar device with somewhat the same sensitivity as Dennis's for use by school-age children.

单选题 The research involving infant Dennis is directed to _____.

【正确答案】 B

【答案解析】解析：首段第3句末的不定式to prevent a lag in the learning process表明了实验目的，另外，文章一开头就提到了本文讨论重点是针对blind children，B为本题答案。A中的the blind指的是所有盲人，而实验研究的只是“盲童”，而且研究的是“学习”的问题，而不是“看”的问题，因此A不正确；选项C中的psychological problems过于空泛；D中的children范围也过宽，原文只关注“盲童”，而不是所有儿童。

单选题 Infant Dennis becomes the subject of the experiment most probably because _____.

【正确答案】 C

【答案解析】解析：首段首句提到的a blind baby，第3句提到的ten-month old和末句提到的infant以及第3句和第4句提到的learning，都表明Dennis成为研究对象是因为做实验的是盲童从小的学习过程，Dennis年龄很小，正处于学习的最初的阶段，符合做实验的条件，因此可推断本题应选C。虽然实验是为了防止盲童在学习上lag behind，但这并不意味着Dennis已经lag behind，因此A不正确；B文中没有提及；D是Dennis成为研究对象后特意为他设计的，并不是使他成为研究对象的原因。

单选题 What can we learn about infant Dennis' device?

【正确答案】 A

【答案解析】解析：第2段首句中的refinement表明Dennis用的声纳定位仪改良自Sonicguide，再根据该句对其功能的描述可以确定A为本题答案。第2段第2句表明the size of a half dollar是包含电池在内的整个声纳定位仪的尺寸，B不正确；C没有原文依据；末段末句中的is working on表明对Dennis的声纳定位仪的改良还在进行当中，因此D不正确。

单选题 "its edges"(Line 11, Para. 2)refers to_____.

单选题 What is Telesensory Systems, Inc. most likely to think about infant Dennis' device?

【正确答案】 D

【答案解析】解析：从末段末句中的school-age children及句中其他内容可以推断Telesensory最可能认为Dennis的声纳定位仪有利于儿童的学习过程，D为本题答案。原文并没有说他们认为学龄儿童才是使用该仪器最适合的年龄，A不正确；B是作者的看法，并非Telesensory的看法；虽然本文从头到尾讨论的都是盲童学习的问题，但第2段首句也提到过成人使用类似的装置，因此C不正确。