liang and er, how to say '2'
how to say 2? in the kid songs i've learned that 'er' is two, but in my courses i sometimes see liang?

are they both the same, like 'two' and 'a pair of'? can i always use 'er' ?

Question

liang and er, how to say '2'
how to say 2? in the kid songs i've learned that 'er' is two, but in my courses i sometimes see liang?

are they both the same, like 'two' and 'a pair of'? can i always use 'er' ?

Answer

Have you been taught about measure words yet?

"二" (er) is the general word for "two", but when you use a measure word, you have to use "两" (liang).

For example:
一，二，三 (yi, er, san) - One, two three
第二 (di er) - second
两个 (liang ge) - Two (of something)

You can't say "二个" (er ge). If you use a measure word, you have to use "两" (liang). "Two" is the only number to which this rule applies.

Answer

pair of一般称作“双、对、副”，
一双鞋
一对夫妻
一副手套

二和两在表示“数量”和“数字”的时候，最主要的区别还是语言习惯上的。

“两＋量词”的用法最多，而“二＋量词”的用法很少。
两个人，一般不说二个人。
……
但“两位”、“二位”说的都比较多。但是“两位嘉宾”多于“二位嘉宾”，也就是说，两个使用更多的不是含义上的差别，而是听觉上的差别。