1.Under the complex and precise control of the central nervous system, a series of instructions are given to the surrounding articulatory organs to complete. 2.The three links for the emergence of language (1) normal hearing; (2) brain language center: the development and maturation of the brain; (3) articulatory organs: breathing, larynx, oropharynx nose and jaw, tongue, lips, soft palate and other normal movements, constitute accurate pronunciation. Language occurs when the nervous system develops to a certain level of maturity. Language development and motor development occur simultaneously, with motor development being the foundation. Communication skills also develop at the same time. Exceptions to this are special cases. Delayed language development is mostly a lag in brain development. 1. not speaking past the age of speech; 2. speaking late or very late; 3. slower or more halting development than other children after starting to acquire; 4. lower language skills despite speaking; 5. lower language application, vocabulary and grammar application than children of the same age; 6. not using sentences; 7. poor communication skills; 8. poor response to questions; 9. difficulty understanding language and following instructions. Common language development abnormalities 1. hearing impairment; 2. mental retardation; 3. autism; 4. developmental aphasia; 5. dysarthria: cerebral palsy, cleft palate, etc. 6. language environmental deprivation.