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TG grammar makes use of transformations. The transformational component helps to convert structures from one level to another. In TG analysis we start with the kernel sentence to which PS rules are applied. The final string of PS rules gives the deep structure. The deep structure is converted to the surface structure through transformations.

TG grammar assumes that there are only kernel sentences at the deep structure level. Transformations are thus used to convert the deep structure to surface structure. Transformations may be obligatory or optional. An example of obligatory transformation is Affix transformation or Affix Switch transformation. Transformations like Negative or Negation, Passive transformations are all optional. This may or may not be applied to the structure. The Affix Switch rule is an obligatory T rule when the affix followed by the verb is changed to a verb followed by affix.

Interrogative Transformation

There are two kinds of interrogatives

      1. Yes/No Interrogatives
      2. Wh Interrogatives

Yes/No interrogatives

Yes/No interrogatives is formed by placing the tense with the auxiliary elements (modal, have, be) to the front of subject NP.

In sentences with no modal have or be, a dummy verb do is supplied. This rule is known as the do support rule or do insertion rule.


These are interrogatives with a question word like who, what, when etc. In this, the auxiliary is shifted to the front of the subject NP. In addition to that, there is also a wh- substitution. The appropriate wh-word is introduced and shifted to the front by w.h- fronting.

Negative Transformations

For negative sentences, the word not is introduced in the auxiliary as an optional element by a rule called Negative placement. The negative element not is placed after the modal, be or do. If there is no modal/have/be, a do is inserted.

The negative not can be contracted by a rule called Negation Contraction Transformation or Contracted Negation. Once not is contracted to n’t, the negative particle n’t always moves along the verbal item.

Passive Transformations

Passive transformations not only reorder the position of subject and object, but also inserts be +en and by into the structure.

Thus TG grammar is a radical theory that provides insight into the language acquisition process.