What's the difference between أَلَمْ تَرَ and أليس تر ?
Hello, how would I know when to use which one, specifically أليس and أَلَمْ ? Thank you

ما هو الاختلاف بين أليس تَرَ وأَلَمْ تَرَ ؟Is أَلَمْ a rhetorical device, in which it isn't expected that the person actually answer the question while أليس is expected to have a response?
A rhetorical device is for example: Isn't the sky blue? Isn't my hair black (and it is)? Don't we all need water to survive? It isn't expected that the person actually reply to the question. It is expected that the answer is already known to the person being asked.

Question

What's the difference between أَلَمْ تَرَ and أليس تر ?
Hello, how would I know when to use which one, specifically  أليس  and أَلَمْ ? Thank you

ما هو الاختلاف بين أليس تَرَ وأَلَمْ تَرَ ؟Is أَلَمْ  a rhetorical device, in which it isn't expected that the person actually answer the question while أليس is expected to have a response?
A rhetorical device is for example: Isn't the sky blue? Isn't my hair black (and it is)? Don't we all need water to survive? It isn't expected that the person actually reply to the question. It is expected that the answer is already known to the person being asked.

Answer

اليس تر is not correct by the way, if you wanna use it say الست ترى / الستى ترين ؟ and it means don't you see?? and the answer will be with بلى for yes and نعم for no. الم تر(ى) is a past tense question, so yes you may say it's more a state a situation than asking a Q. Or yoy may want the other person to answer, it depends on the tone you say it with. الم ترى الكتاب الذى كنت اقرأه بالامس لقد كان هنا ؟ and الم تر هذا الفيلم بالعام الماضى؟! and there is a sentence in Quraan such as ": أَلَمْ تَرَ أَنَّا أَرْسَلْنَا الشَّيَاطِينَ عَلَى الْكَافِرِينَ تَؤُزُّهُمْ أَزًّا  {مريم: 83}." this one is a statement and it doesn't need an answer of course. 
I hope you got it, if there is any thing you didn't understand feel free to ask^^

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"انت فاهم صح "ويسمى "سؤال منفى " واجابته (نعم السماء زرقاء)  أو (بلى السماء زرقاء)

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Isn`t my hair black? =أليس شعرى أسود؟

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Isn`t the sky blue =اليست السماء زرقاء

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Isn't the sky blue?  = أليست السماء زرقاء

نعم السماء زرقاء  = بلى السماء زرقاء