(continued)
18. The sound as in /let/
Keep the tip of the tongue  behind the upper teeth.Then produce sound and spread the tongue in the mouth to touch the lower teeth.
e.g. live,feel,cell etc.
19. The sound as in /hat/
Just open the lips and produce air from the back of the mouth.This is voiceless sound.
e.g. hat,hot, who etc.
20. The sound as in/yes/
Keep a small gap between the tongue and the roof of the mouth and produce voice.
e.g. yesterday,year, university etc.
21. The sound as in /what/
Round the lips and produce the sound like 'oo'.
e.g. wind, away, white etc.

( to be continued)