单选题
Videodisc holds great promise of helping to meet the needs of American schoolchildren who have problems seeing, hearing, speaking, or socializing. Almost eleven percent of the students aged 3-21 in this country have an impairment that affects their ability to benefit from a regular education program. Handicapped students require special education because they are often markedly different from most children in one or more of the following ways: mentally retarded (发展迟缓的) learning-disabled, emotionally disturbed, deaf, visually handicapped, physically handicapped, or other health impairments. The education of these handicapped children is rewarding but challenging.
A special education student usually needs a longer period of time to acquire information. Repetitive teaching techniques are often beneficial, and indefatigable (孜孜不倦的) consistency on the part of the teacher is frequently necessary. Interactive videodisc courseware has characteristics that can be capitalized upon to meet the challenges that special education poses. A videodisc program is infinitely patient. Repetition of any videodisc lesson can continue endlessly, and designers can assure absolute consistency within a program. Most important, according to special educator William Healey of the University of Arizona, is that videodisc "adds an extra dimension of realism for children who need graphic representations."
Healey explained that deaf and mentally retarded children especially have difficulty grasping figurative language and higher-order language concepts. He believes that for special education, the power of videodisc lies in the ability of the technology to visually represent language concepts normally taken for granted by non-handicapped persons. Complex figurative language forms such as idioms and metaphors come most readily to mind as being difficult for handicapped learners.

单选题 The special education mentioned in the text is mainly concerned with______.

单选题 A videodisc courseware is beneficial to those who have study difficulties because______.

单选题 According to Professor Healey, we may infer that mentally retarded children perhaps______.

单选题 The best phrase that summarizes the main idea of the text is______.

单选题 The word "impairment" (Line 2, Para 1) probably means______.