Routinely, babies start to call out for mommy and daddy at the age of one, can say simple sentences of 3-4 words at the age of two, long sentences of 8-9 words at the age of three, can pronounce 90% of the sounds at the age of four, and should be able to pronounce all the sounds at the age of six. For children’s language development, it is generally believed that 8-month-old children can slowly and gradually transition from meaningless to meaningful pronunciation. As the child’s cognitive and imitative abilities develop, by 9 months of age the child begins to pronounce the first sound. The pronunciation may not be clear, but as long as it is a fixed pronunciation and represents a fixed meaning, it is a meaningful pronunciation. From one to two years old is the child’s language sensitive period. At this time, the child will be very sensitive to language, no matter who speaks, the child’s eyes will stare at whoever. At one and a half years old, children can usually say about 20 words. At the age of two, the child can say more than 50 words. The period between the ages of two and three is the child’s language explosion, which can be at the beginning of the age of two, or at the end of the age of two near the age of three, in which the child’s language will explode like a well. The rate of language development varies from child to child, with girls generally speaking a little earlier than boys.