when to use 'er' and when to use 'liang'

[goldie]

i'm teaching beginners chinese to adults and i'm sure there will be many times when i have to ask how to explain one thing or another. today i need to ask this...how do you explain when to use 'er' and when to use 'liang' as in the number 2? i often say 'liang bai' instead of 'er bai' as well as 'liang ge' instead of 'er ge' but why? and how do i explain it to them? xie la!

[Canlendoor]

不太好区分啊，口语中常用“两”而书面或正规表达中用“二”多吧，如果2在十位或个位上，只能用“二”，如“二十二”，在其他位置上可混用，222“两百二十二”可以是正确的表达。另外当“两”用做重量单位时，前面只能跟“二”如“二两”……

还有别的……例子一时想不到了

It is not so easy to distinguish...In spoken Chinese, we usually use"liang" instead of "er"(of course using "er" is perfectly correct in grammar, but we don't quite use "二个 er ge") while we consider 'er' more formal. If the number 2 is in 2? or ?2 (means twenty-x or x-ty-2,including twelve...ninety two for example) we can only use 'er',like in 22 (er shi er). In other cases both 'er' or 'liang' are correct, they re mixed. Like 222 saying "liang bai er shi er" can be correct expression. And, when "两" is used as a mass(or weight????) unit, we can only put "er" in front of it.like 二两-er liang.

and there are still some other rules...I cannot find suitable examples at present...

[Canlendoor]

这个不太好解释...

我想想,再回复你

[Quest]

we had a thread on this: http://www.chinese-forums.com/index.php?/topic/5526-%e4%ba%8c-and-%e5%85%a9

[goldie]

thank you Quest for pointing me in that direction. i like the rule 'LIANG hates SHI'. MAN, i wish i knew how to input characters in these forums, or anywhere else as a matter of fact. i'm knew to all this typing in hanzi business, only just downloaded macros so that i can do the tones for PINYIN in Word. that's as far as i've got.

[Ferno]

liang is used for time, right? ie "liang dian" 2 o'clock?

[amego]

when counting numbers, like 1-10 use 二 er4

when telling the time, like two o'clock use 两点 liang2 dian3

when counting WITH COUNTERS, use 两　like 两个，两只.....

二　is more of second, as in first, second, third, so it is 第一，第二，第三

one example is storeys...

二楼 second storey

"他住在二楼." He lives on the second storey.

两楼 two storeys

"这间屋子有两(层)楼高." This house is two storeys high.

take a look at this previous post too, its about the same topic also

http://www.chinese-forums.com/index.php?/topic/5526-%e4%ba%8c-and-%e5%85%a9&highlight=er4

hope this helps