When does the - ing form of an English verb need to double the last letter? What are clear consonants and turbid consonants?

When does the - ing form of an English verb need to double the last letter? What are clear consonants and turbid consonants?

In French, consonants are divided into light consonants and voiced consonants. When light consonants are pronounced, the vocal cords do not vibrate, such as: [k] [S] [F] [P] [t] voiced consonants. When voiced consonants are pronounced, the vocal cords should vibrate, such as: [g] [Z] [v] [b] [D] monosyllabic words: a