a horse is an animal为什么NAIMAL前面要加AN,

a horse is an animal为什么NAIMAL前面要加AN,
a horse is an animal
为什么NAIMAL前面要加AN,

a horse is an animal为什么NAIMAL前面要加AN,
请记住,英文中的名词,一般情况下都不能光秃秃的,一定要有冠词.定冠词,不定冠词必须择一,或者是复数形式.比如：
A bee is an insect. ---- an
Bees are insects. ----pl.
The bee is flying around the tree. --- the
Bees are flying around a tree. --- a
Bees are flying around trees. --- pl.

不行,这里代表:一种动物.

就是一种习惯，不加不可以
不加用复数Horses are animals也可以吧

一种动物.
不加也可以.但最好还是加上.

马是一种动物。可以翻译为;
A horse is an animal.
Horses are animals.