She is sitting in back of me.

She is sitting in the back of me.
She is sitting at the back of me.
She is sitting at back of me.

She is sitting in front of me.
She is sitting in the front of me.

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In this situation, are all the expressions grammatical?
Regardless 'the', is each pair the same?

If she is behind you, then the best sentence would be "She is sitting in back of me. "

"She is sitting in front of me."

The use of "the" would not be correct there.

Can't we use"She is sitting at the back of me".

I could find the idiom, 'at the back of' in the dictionary.

However, do yo mean in this case, the idiom is not used?

I have rarely heard "at the back of" used. Guru gave you the best answers.

Out of the four expressions you provided, only two of them are grammatical and convey the intended meaning.

The correct expressions are:
1. "She is sitting behind me." (Use "behind" instead of "in back of.")
2. "She is sitting at the back." (The word "of" is not needed in this expression.)

The expression "She is sitting in back of me" is not grammatical. The correct phrase to use is "behind me" instead of "in back of me."

Similarly, the expression "She is sitting in the back of me" is also incorrect. Instead, you should say "She is sitting at the back" which means she is sitting further back in a specified area.

Now, let's compare the two correct expressions:

1. "She is sitting behind me." and "She is sitting at the back."
Both of these expressions convey the same meaning, which is that she is seated in a position behind you or situated further back in a specific area.

Moving on to the expressions involving the front:

The correct expression is: "She is sitting in front of me."

However, the expression "She is sitting in the front of me" is not grammatically correct. You should omit the word "the" in this phrase.

To summarize, only the expressions "She is sitting behind me" and "She is sitting at the back" are grammatically correct. The others contain errors or unnecessary words.