"Your book is under the television."

Translation: 你的书在电视下面。

[olorino]

你书在电视的下面
Is this really not accepted?

[o-chefe]

We can skip 的 when it is a close personal relation

[Jasmin358807]

Why don't we need ”的” after ”电视”? Would it be wrong to use it?

[chetlin]

I used it and it was accepted.

[maartendoc]

电 (diàn) = lightning/electricity
视 (shì) = to reveal/to show/to look at
电视 (diànshì) = television

We saw 电 before in:

电 (diàn) = electric/electricity
影 (yǐng) = picture/image/film
电影 (diàn yǐng) = movie

打 (dǎ) = to beat/to strike/to hit
电 (diàn) = electric/electricity
话 (huà) = dialect/language/spoken word/speech
打电话 (dǎ diàn huà) = to make a telephone call

[Meebas]

下头 is another alternative to 下面

[freymuth]

Is the 面 really necessary here?

[Cinnamon5230]

Technically, no.

But in daily conversation, almost yes.

[freymuth]

Almost yes? So, no?

[Cinnamon5230]

Most people use 上面/下面/前面/后面 instead of 上/下/前/后 in conversation. The single character preposition gives a literary/archaic feeling and may confuse the listener.

（However, the combination 左面/右面 are incorrect, 左边/右边 are correct.）

In some cases, using the single character preposition is strictly prohibited in modern Mandarin, like after a pronoun or a person's name:

你后面有一个人。 There's a man behind you.

Here you can't use 后 to replace 后面.

2-character preposition is a modern feature. Classical Chinese always uses single character prepositions. Modern Chinese still has its influence. You can see classical usage of prepositions like 其后 (其 is the third person pronoun in classical Chinese) in writing and occasionally in speaking.

[Xinmei20]

你的书在电视机下前