The first day of school in the China falls on 1 September, or the first Monday following if September 1 is a Friday, Saturday, or Sunday. In northeastern China, schools open on Monday in mid-August after summer vacation.
3) Improper heating profiles setting lead to unbalanced heating zones temperature inside heating furnace, which causes uneven glass temperature on both different parts of the glass sheet and between the top and bottom glass surfaces, thus may brings irregular white haze on glass surfaces.
Headaches due to glasses is something often easily sorted out. Depending on whether you wear glasses or contact lenses, your usage habits, and when the headaches occur, you can troubleshoot the cause. I have had what feels like countless cases where glasses were ultimately the cause of headaches and migraines.