There is an interesting situation here which would be a paradox unless we were willing to make assumptions on the nature of the learner: as investigators of the nature of language, it is preferable to concentrate on understanding; the objects that are to be understood are sentences; the sentences that are actually heard are frequently “degraded specimens ’’from a grammatical point of view-they are semisentences at best; on the other hand, the understanding of semisentences is apparently more difficult proper sentences. We first seem to learn the rules and principles underlying grammatically correct sentences, and only by virtue of having acquired these can we begin to understand semisentences. (This becomes particularly evident in the acquisition of a second language by a good lecturer or presented in print, long before we can understand a conversation which is heavily loaded with semisentences ) . The paradox is this: if the child’s task is to abstract principles that generate correct sentences, but is presented indiscriminately with semi- and proper-sentences, how can the correct principles be established, and why or how does his understanding of sentences become fairly explainable in terms of a grammatical theory? The assumption that we have to be willing to make here concerns the cognitive machinery that we must suppose to be developing in the child.
這裡有一個有趣且矛盾的情勢，除非我們願意在學習者的本性上假定︰作為自然語言的調查者，比較能專心於理解，而目標是理解句子；實際上聽到的句子經常是「被降級的樣本」，從文法的觀點上來看他們是不完全句子（semisentences）； 另一方面，理解這些不完全句子顯然是比理解那些句法完整的句子要來的困難。我們一開始似乎會先學習規則以及文法基礎來修正句子，利用習得的優點讓我們開始理解不完全句子。 (這顯然成為一個演講者或是書寫者習得第二語言的方法，很早以前我們就用來理解含有大量不完全句子的口語)。矛盾的是：假如孩子對於收集正確句子的原則是很抽象難懂的，不過隨意呈現不完全句子以及完全句子，他是如何建立正確的原則，還有為什麼或者如何在文法理論中運用他的句子理解能力而能夠完全解釋？這項假設讓我們願意將這樣的關係把認識文學橋段與我們推想應該是發展於兒童連結在一起。
If the most promising source-material for a theory on syntactic mechanisms is understanding, what data should we use to construct a theory on the development of syntax in children? His actual utterances may, in certain cases at least, be irrelevant to his development of syntactic mechanisms(for instance, in children with severe psychiatric disease who may not choose to speak, or who prefer to make animal noises, or in children whose noises cannot be understood). By and large it is true that young children can understand more than they can say.＊
Children between 18 and 36 months seem to have a tendency to run constantly through their repertoire of capacities. This is also reflected in their verbal behavior in that during this period the gap between their understanding and speaking capacity normally remains fairly constant and predictable. This may be tested by asking them on the one hand to execute certain verbal commands or to point to pictures that are being described to them in more or less complex sentences, and on the other hand to require them to repeat accurately sentences that are given them. Since a sentence contains so much detail we cannot repeat it correctly upon a single presentation unless we can apply grammatical principles to it by means of which the mass of information can at once be recorded and thus processed in much simplified from Mehler and Miller, (1964). The utterances of a child who is just beginning to speak (normally not much later then 30 months) may thus reflect the stages that his development of language capacities, particularly understanding have traversed, even though one may actually have taken place some 2 months before the other. By about 30 months, however, production soon becomes as unreliable an indicator of language capacities as is the case in the adult. Unfortunately, no studies have yet been published that have undertaken systematic research on the development of grammatical understanding of the child at this age and older. Even the best studies have relied too heavily on production.
18~36個月大的小孩似乎習慣經常使用理解能力範圍的內容。他們的理解和說話能力常態來說是可預期的，這也是這段期間表現在言辭上的行為。這或許可以用問的方式來做測驗，一方面實行固定的言辭上的命令，或者是指出圖片並且使用或多或少的完整句子來描述他們，另一方面要求他們準確地重複句Mehler 和 Miller(1964)表示，因為一個句子包含很多細目，所以我們在無法正確地一次的發表中重複它，除非我們可以藉由對照資訊的語法規則立刻紀錄以及使過程簡單化。一個剛開始說話的小孩(常態來說不會晚於30個月大)，他的語調或許反應了語言發展能力的階段，尤其是理解的經過，甚至事實上取代兩個月前就進行其他了。然而，大約30 月，語言能力的指標生產不久成為不可靠，變得像成年人那樣。不幸地是，沒有研究發表承擔有系統對的研究語法理解孩子的發展在和年紀更大的這年齡。即使在生產上倚賴最好的研究已經太嚴重。
(b)How Mature Speakers Understand Sentences. Some insight into this problem is provided by asking ourselves why a sentence such as
They are boring students has two meanings. Here the explanation is quite simple; we may choose to link the word boring to the word are as in Fig.
Each of the circles may be characterized by an abstract name such as shown in Fig. 7.4. Instead of writing the names on cylinders or circles we might set up a list of definitions such as shown in Table 7.2. Similar information as that shown in Fig. 7.4 as a cylinder-diagram and in Table 7.2 as list of definitions is represented by Chomsky in the form of a tree diagram which he calls phrase-marker. The grammatical principles illustrated in Figs. 7.3 and 7.4 may be diagrammed by phrase-markers as in Fig. 7.5.
每個圈都可能如圖7.4中所示以摘要詞性為特點。 不是寫那些名字在汽缸上或者環繞如表格7.2中所示我們可能建立這些定義的目錄。在圖7.4顯示一張汽缸圖解為相似的訊息 並且在表格7.2列出Chomsky定義的目錄稱為片語製造者的一張樹狀圖。在圖7.3以及圖7.4裡說明的語法原則。在圖7.5 片語製造者可能用圖表示。
 But Roger Brown (personal communication), in his extensive investigations of the first steps toward language acquisition, has found that this is not always and necessarily true. For example, there were instances in his sample in which plural inflections were used productively at time when experiments on the child’s semantic progress indicated that he did not yet know what this particular suffix signals. Similar observations were described by Fraser et al. (1963).