Translation:You cannot look at the textbook during the exam.
Surely cannot and must not are interchangeable here? Must not was marked incorrect.
I'd argue cannot is more correct and what they're more likely to say - as in it's not even a possibility, you won't have them during the exam etc. Must not feels more like it's acknowledging that's an option, but you shouldn't do it, so it feels less assertive than outright saying "you won't be doing this!"
But yeah, either should be accepted here
Where do you get the idea that you won't have your textbook during the test? Having access to them is much more likely in schools in Japan, but obviously you must not look at them.
What nuance does putting the は particle after で add? Would the translation change without it? Both are grammatical, right?
It makes it contrastive. In the test you can't look at the textbook, and disregard any other situations when it's normally fine. It's still grammatically correct without the は.
I'm actually more confused by its presence, as now this sentence seems to have 2 topics. Since it's both grammatically correct, is one favoured (or more popular) over another?
I look at で as "in/during" and は as "as for", so transliterated it becomes "test" "in/during" "as for" -> "as for (in/during test)". This means that は encapsulates and makes テストで the subject ("in/during the test" is the subject).
Ultimately, its "As for (your time) during (the) test, ...". The は isn't necessary to my knowledge, since テストで also means "during the test". The は just draws extra emphasis that what follows deals specifically to "during the test".
To add to the other reply, Tae Kim puts this use of the は particle in perspective pretty well. He describes it as a topic (rather than subject) indicator, and translates it roughly like "as for [topic]".
In this context, it's there to indicate that you not being allowed to look at your textbook is specifically the case when you are taking the test ("as for [in/during a test], you cannot look at your textbook").
This needs context for if it is talking about "I" or "You". It's naturally left out of natural speech. if i had context then i could tell but there is none . If you are going to test someone on this kind of stuff then you allow both to be right
Using "-te wa ikemasen" is forbidding someone from doing something. It's not usually a phrase you would use about yourself, it's something that you would say to someone else.
I'm still learning, but "I/we cannot look at the textbook during the exam" seems like it should be right to me
"You MAY not look at the textbook during the test." You can look at it. But there will be consequences. So you MAY not look at it. It is about not having the permission to do so.
They're both right colloquially, but people who are first learning Japanese are thinking that "-te wa ikemasen" means cannot as in it's not possible, not as in it's not permissible, so they might be learning it wrong.
That would be テストでは教科書を見ることが許されていません。 The (unwritten) subject of the Japanese sentence is the person looking at the text book ('you'). In your sentence the subject is 'looking at the textbook'. Therefore, your answer is not correct.
The usability of Duolingo for Japanese is severely hampered by the rigidity of the proposed translations.
What is up with the seeming double use of topic marker in the Japanese sentence? Am i wrong to read テストでは as pairing で with テスト, and then pairing テストで with は again, so that the topic indicated by the は is "on the test"? Additionally, how would you break down the parts of 見てはいけません? So far, i figured that いけません was used as a verb inflection/conjugation, and not as a separate word by itself, like the separation of 見て and いけません here would indicate. I'm also unsure about how to think of 見て when it is modified by は. Would somebody please break this down for me?
The plural "textbooks" was marked as mistake, is it false here? I wonder how Japanese distinguish between singular and plural when necessary.
Both the singular and the plural are correct. I'm a Mandarin native speaker, we usually don't distinguish between singular and plural either. (The concept of plurality is not that important in the languages' logic.) If necessary, we use words like "most" books, "part of the" books, or directly tell the exact number like "one (with a classifier)" book.
"During the test, you cannot look into your textbook." isn't correct? The problem is not "to look at", but "to look into" the textbook.
I was marked wrong for "look in". Apparently it is forbidden even to cast your eye upon ("at") the cover of this powerful book.
Cannot means quite literally are unable to. The equivalent in Japanese would be できません.
You WANT "must not".
"Can not" can mean either "not able to" or "not allowed to" in English. In this context, one can use "can not" to mean the latter.
"You must not look at the textbook during the exam." I think this is better. ～してはいけません is stronger than ～してはなりません, like must and may/can (which tends to the Commonwealth vs. USA divide in my experience, though even I don't mind can in first-person, here it's just plain rude).
You wouldn't say this in the general case. The scenario is of a teacher reminding a class of the exam rules before starting. Also, the では heavily implies a particular exam.
"You 'may' not look 'in' the textbook during the exam" was marked wrong? this seems like an oversight.
I feel like "use" kind of means the same thing in this context and is actually a more implication-accurate translation.
見ていけません in two sentences: I translated "it's forbidden to look at ..." in both and once it was ok, the other not
You cannot look at textbooks during the test. This should be ok too. It conveys exactly the same concept.
Exam and test are both english-acceptable. Also I think we can put the 'during the exam' at the begining of the sentence as well : 'During the test, you cant look at the textbooks'
Why do i get marked wrong for for saying 'in the exam' instead of 'during the exam'?
Looking in the textbk (for reference...) seems more approoriate than '...at'.
Duo is so inflexible about translating as "I" or "you" that we must end up memorizing peculiar answers, rather than learning Japanese.