The Classification of Words

Extensions
§ 467. Extensions are adjuncts of adjectives, adverbs and adlinks in a sentence. They differ from complements and attributes in being usually modifiers of modifiers, or ter-tiaries, in the terminology of O. Jespersen.
¹ Op. cit., p. 47.
² В. Л. Каушанская and others, op. cit., p. 259,
Л. С. Бархударов, Д. А. Штелинг, op. cit., p. 360, etc.
268
In a simple sentence extensions may be single words or combinations of words, including complexes.
Doreen's voice sounded too brisk and too loud. (Cusack).
Her little resolute face under its copper crown was suspi­ciously eager and aglow. (Galsworthy).
The creature's eyes were alight with a somber frenzy. (London).
Then he became aware of Abbey standing before the big open fire in the hall. (Cronin).
§ 468. W. Francis distinguishes between such 'adjective qualifiers' as very, quite, rather, pretty, mighty, somewhat, a bit, a little, so, too, more, most, less, least, enough, indeed, on the one hand, and such as exceedingly, enormously, etc., on the other, since the latter "are marked as adverbs by the adverb suffix -ly and can appear in positions regularly occu­pied by adverbs." ¹
We do not think this distinction relevant when analysing extensions as a part of the sentence which covers different morphological classes of words. Besides, most of the 'adjective qualifiers' are connected with more than one part of speech, as W. Francis himself admits: "Since qualifiers also appear with adverbs, they are not exclusively adjective determiners" ².
Connectives
§ 469. Connectives are linking-words considered as a second­ary part of the sentence. They are mostly prepositions and conjunctions.
She played and sang to him. (London).
Connectives differ from the previously mentioned second­ary parts of a simple sentence in not being, as a rule, adjuncts of certain head-words.

1. 
   They usually connect two words both or neither of which
   might be regarded as their head-words;
   
2. 
   The words they connect belong to various parts of speech.
   With conjunctions this refers to both right-hand and left-
   hand connections (see § 358). With prepositions it refers
   

279.
¹ The Structure of American English. New York, 1958, pp. 278— Ib