2.2 causes of LD
2.2.1Mental Retardation(智力迟钝 智力缺陷) Approximately 2.5 percent of population Categories Mild IQ 52-68 Usually absorbed into the community where they work and live independently. Moderate IQ 36-51 Capable of learning self-care skills and working within a sheltered environment; live semiindependently,with relatives, or in a community residence. Severe IQ 20-35 Capable of learning some self-care skills and are not totally dependent; often exhibit physical disabilities and deficits in speech and language. Profound IQ below 20 Capable of learning some basic living skills but require continual care and supervision; often exhibit severe physical and/or sensory problems.
2.5.2 semantics
Limited expressive vocabulary and slow vocabulary growth Few or decontextualized utterances, more here andnow; more concrete meanings Limited variety of semantic functions Relational term difficulty Figurative language and dual definition problems Conjunction confusion Naming difficulties may reflect less rich and less elaborate semantic storage or actual retrieval difficulties.
