Linguists suggest that speech milestones are reached in a fixed sequence and at a constant age, but there are cases where speech has started late in a child who eventually turns out to be of high IQ (Intelligence Quotient)。 At twelve weeks a baby smiles and utters vowel-like sounds; at twelve months he can speak simple words and understand simple commands; at eighteen months he has a vocabulary of three to fifty words. At three he knows about 1000 words which he can put into sentences, and at four his language differs from that of his parents in style rather than grammar.
語言學家認為,言語在一生中的各個階段是按固定的先後順序,在某一定的年齡分別達到的,但也有若干情況,某些孩子開始說話晚,結果其智商卻很高。十二週的嬰孩會笑,發出元音似的聲音;十二個月的孩子可以說簡單的詞,懂得簡單的命令;十八個月的孩子有三到五十個單詞的詞彙;三歲的孩子懂得一千單詞,並且能夠組成句子;到了四歲時,孩子的語言與其父母的語言只是在風格上而不是在語法上有所差異。
Yǔyán xué jiā rènwéi, yányǔ zài yīshēng zhōng de gège jiēduàn shì àn gùdìng de xiānhòu shùnxù, zài mǒu yīdìng de niánlíng fēnbié dádào de, dàn yěyǒu ruògān qíngkuàng, mǒu xiē háizi kāishǐ shuōhuà wǎn, jiéguǒ qí zhìshāng què hěn gāo. Shí’èr zhōu de yīnghái huì xiào, fāchū yuán yīn shì de shēngyīn; shí’èr gè yuè de hái zǐ kěyǐ shuō jiǎndān de cí, dǒngde jiǎndān de mìnglìng; shíbā gè yuè de háizi yǒusān dào wǔshí gè dāncí de cíhuì; sān suì de Háizi dǒng dé yīqiān dāncí, bìngqiě nénggòu zǔchéng jùzi; dàole sì suì shí, háizi de yǔyán yǔqí fùmǔ de yǔyán zhī shì zài fēnggé shàng ér bùshì zài yǔfǎ shàng yǒu suǒ chāyì.