2. Literature review

2.1 The relationship between sentence combining and syntactic complexity

The goal of sentence combining is not to produce longer sentences but rather to develop more effective sentences while syntactic complexity is one of the most crucial measurement indexes for sentence combining ability. Syntactic complexity refers to the number and type of transformations used in a sentence. Fodor, J amp; Garrett, M (1967) have maintained that a sentence becomes more complex as more transformations are added. In other words, the more complex one sentence#8217;s syntax is, the higher one#8217;s sentence combining ability is.

2.2 Factors influencing syntactic complexity

Syntactic maturity is manifest in the many aspects, such as the length of each unit, the amount of clauses embedded and the scope of structure type ( Ortega 2003: 492).

Hunt (1970) identified three main indexes to establish the level of text productions' syntactic complexity. The first one was the Media Length of Minimal Terminable Syntactic Unit (T-Unit). A T-unit, defined by Hunt as a main clause and any subordinated clauses attached to it. The second index was the clause- Length and the last one, the Syntactic Complexity Index (SCI), which showed the number of subordinated sentences for every T-unit.

So far, researchers have quantized syntactic complexity through various index, such as type of words, type of sentences, sentence length and subordination ratio.

Some of the earlier studies counted the proportion of nouns, prepositions and so forth used by children of various ages. But Templin (1957) reported that the proportion used by a 3-year-olds is about the same as that used by older children. So we must conclude that the distribution of speech, though in a quantized and objective measure, is not revealing for the study of later development.