Under what circumstances would you subscript the light tone?

After the structural mood auxiliary word.

A special tone, called soft tone, sometimes called fifth tone, is not standardized in Chinese Pinyin.

Light tone is not a simple phonetic phenomenon, it is closely related to grammar and has strong regularity. The following seven grammatical elements should be read softly:

1. The modal particle "Ba, Ma, Na, Ah" and so on. For example, eating, walking and running.

2. The structural auxiliary word "de, de and de". For example, my books go slowly and run fast.

3. Dynamic auxiliary words "le, zhe, guo". For example: gone, seen, and been.

The suffix of nouns is "man, son and head". For example: you, the house, the stone.

5. Nouns are followed by "upper, lower and inner". For example: desk, underground, yard.

6. The second syllable where monosyllabic verbs overlap. For example, look, say and ask.

7. Personal pronoun "I, you, he" as the object. For example, please find me and trouble him.