A blue pants成立吗,老师说pants是复数,可是又可以写成a pair of pants.我都混乱了

pants 只用于复数形式,习惯的表达方式是 a pair of pants .
虽然汉语我们说 一条裤子,英语要说 a pair of pants .
这个说法来自裤子的两条裤腿.
例句：
Did you buy your pants?
Have you seen my pants?
I bought a pair of pants yesterday.
I bought some pants yesterday.
不要从个逻辑去分析,英语是这样说的.
我是加拿大人,前英语老师.