Which of the statements about drinking etiquette are correct?

Which of the statements about drinking etiquette are correct？

A、Liquor glasses are filled three quarters full.

B、Seniors, superiors, and guests are served first.

C、To show respect and humility, keep your liquor glass lower than others’ when cheering.

D、The host usually makes the first toast.

此题为多项选择题。请帮忙给出正确答案和分析，谢谢！