2. People who can produce the basic sound, however, because of the whispering sound in the oral cavity, they only repeat single syllables and cannot proceed to speech.
3. People who mastered the swallowing method, and cannot make continuous vocalization.
It is easy for instructors to teach persons who are taken to the tide of good progress, and happy doing practice so that instructors can only teach the points to those persons. However, there are people who are left behind in the class, get disappointed as time passes by, and become giving in. Instructors should encourage them and immediately correct their speech, otherwise they will be dropped out for good.
Here, I would like to suggest some of the solutions to that problem. As for problem No.1, you should adopt either the tea sipping method or swallowing method, in which air is taken into the esophagus.