Yabla video uses of

gān
zuǒ
经过 jīngguò
长期 chángqī
研究 yánjiū
Hòu
作出 zuòchū
判断 pànduàn
undertook lengthy research and concluded that
yóu
zuò
yáng
shí
xiè
liáng
zuǒ
并称 bìngchēng
chéng
mén
先生 xiānsheng
and together with Youzuo, Yangshi, and Xieliang was known as one of the "Four Apprentices of Chengyi."