1.
Know, late, time and day: the vowels of these four syllables are "-i" behind the tip of the tongue, so it is difficult to grasp the position of the mouth and tongue when pronouncing. The purpose of treating these four syllables as a whole is to avoid the learning difficulty of the vowel "-i" after the tip of the tongue.
2.
Zi, Ci and Si: The vowels of these three syllables are all pre-vowels "-i", so it is difficult to grasp the position of the tongue when pronouncing. The purpose of recognizing these three syllables as a whole is to avoid the learning difficulty of the vowel "-i" before the tip of the tongue.
3.
Ye: This syllable can be regarded as a self-contained syllable of vowel ie, and it can also be regarded as a syllable composed of initial Y and vowel Mi. According to previous understanding, in order to avoid teaching spelling rules, it should be regarded as a whole ("Scheme" stipulates that vowel ie has its own syllable, so I will change it to Y); If you read it as a whole according to the latter understanding, it is to avoid teaching the low vowel "mi" in the first half of the tongue.
4.
Yi, yin, ying and wu: These four syllables are formed by adding Y or W to the four vowels I, in, ing and U according to the spelling rules stipulated in the scheme. The purpose of taking these four syllables as a whole is not to teach spelling rules.
5.
Yu, Yu, yun, yuan: These four syllables are formed by adding Y before vowels ü, üe, ün, üan according to the spelling rules stipulated in the scheme. Reading these four syllables as a whole is also to avoid teaching spelling rules.
The syllable PS: yan does not belong to the above five situations, so it is not listed as a whole recognition syllable. A in strictness is equivalent to a, but it is not a ... An in Yan is not the sound of "An". Actually pronounced n, the international phonetic symbol is [ε n]. It is feasible for some teachers to teach "Y (clothes) -an (é n)-Yan (cigarettes)".