"Her book is under the chair."
I'm not fluent in chinese but I can speak a moderate amount and I've always heard this with a 面(+儿 since my family is from beijing) after 上 and 下 as in 她的书在椅子下面。Why does duo not use 面?
Doesn't 'mian' imply a surface? I feel as if this is what I learned and heard often. (I also studied abroad in Beijing).
You're correct Daniel, and as to whether Duolingo should accept 面 - I think they should accept it. I am an ABC living in a large Chinese community, and yeah, it's used a lot here.
我尽量用简单的中文，例句“书包在桌子上”和“书包在桌子上面”和“书包在桌子下面”。是的，可以说上面也可以说“上”一个字，只能说下面。对Duolingo来说这太难了… Here goes your answer. As these sentence“sth在桌子上"and"sth在桌子上面"and"sth在桌子下面"are widely accepted. Yes,上面and上(without面). But you'd better use下面rather than下. Of course, no matter下or下面, just the issue of usage rate. The“在sth上“is more common than“在sth下“. The sentence“在桌子下”is right, too.I think it's too hard for Duo. BTW, the current Chinese language version is different from 100 years ago totally, which is called“文言文”. Chinese is pretty hard for native speakers, too. Be patient.
I tried "她的书在椅子下面。" and this was marked wrong with no clear explanation. An online search shows that "在椅子下面" is a commonly used phrase. Is this correct with or without the "面"? Is there any difference in meaning?
There isn't! It's a bit of a cultural thing to add 面 - and completely unnecessary - but it's usage is very common!
在下以一个中国人的身份为君解惑，你是对的。我们会说在下面，在上面。一般不会说在什么什么下，但是我们会说在什么什么上。 I'm here to answer your question as a Chinese, you're right! We would say在下面，在上面, not在something下，but we also say在something上, without面. One more thing,“在下”means "I", not under something.
Not every time. And it's necessary this time. 不一定，这次真的需要，不然不通顺，中文还讲究韵律和其他的一些东西。中文的语法复杂就复杂在不能简单的一概而论，需要分得特别细。Just ignore it if you don't recognize these Chinese character.