12. How is vowel length conditioned positionally?

Qualitative difference is the main relevant feature that serves to differentiate long and short vowel phonemes because quantitative characteristics of long vowels depend on the position they occupy in a word:

1. they are the longest in the terminal position: bee, bar, coo, her, law, car,

2. they are shorter before voiced consonants: bead, bard, cool, term, lard, card',

3. they are the shortest before voiceless consonants: beet, Bart, hoot, Turk, loose, cart.

To observe the quantity, or length of vowels in different posi­tions, it is advisable to do contrast exercises, e.g.

bee — bead — beet bar — Bard — Bart car — card — cart

13. What distinctive, oppositions illustrate the classificatory principle of vowel stability in articulation?

The principle provides the basis for the following distinctive oppositions:

(1) Monophthongs vs. diphthongs

bit—bait bid—beard dead—dared cot—coat

In these pairs the monophthongs /i, e, o/ are opposed to the diphthongs /ei, ia, еэ, эй/.

kit—kite debt—doubt John—join

In these pairs the monophthongs /i, e, o/ are opposed to the diphthongs /ai, au, 01/.

(2) Diphthongs vs. stable vowels

bite—bee bait —beet boat—boot pail—pool lake—leek beard—bead raid—rude care—coo

In these pairs the diphthongs /ai, ei, ю, эй, вэ/ are opposed to the jr., u:/.

14. How are diphthongs subdivided according to the tongue movement from the nucleus to the glide?

According to the movement of the tongue within the articula­tion of the diphthong from the nucleus to the glide, diphthongs are subdivided into closing and centring. The method of minimal pairs helps to establish 20 vowel pho­nemes in the phonological system of English vowels:

12 monophthongs: /i, e, se, a, v, o:, u, л, з:, э, i:, u:/> 8 diphthongs: /ei, ai, oi, 1Э, вэ, иэ, аи, эй/.