Why the video does not have subtitles

Iā€™m not good at english,Why the video does not have subtitles

Subtitles are really expensive to have made and machine-generated ones are often not very good especially for technical material. What language would you need the subtitles in?

I am Chinese.I can read most of the English words,but listeting English words the is very difficult

We do order subtitles for our videos. Sometimes they take a little while to arrive, but they will be there eventually! :]