A student asks "じしょ を つかって も いい です か?"
Teacher replies" いいえ だめ です"
I want to know, if possible, how could he have used だめ です to say the full sentence of "no, you cannot use the dictionary" or is だめ です equivalent to english "no you can't"?
A student asks "じしょ を つかって も いい です か?"
Teacher replies" いいえ だめ です"
I want to know, if possible, how could he have used だめ です to say the full sentence of "no, you cannot use the dictionary" or is だめ です equivalent to english "no you can't"?
The full sentence would be いいえ、辞書{じしょ}を使{つか}っては駄目{だめ}です, literally translating 'No, you cannot use the dictionary. You could also say いけません or なりません in place of 駄目{だめ}; all three can also be used in plain form, as 駄目{だめ}だ, いけない, and ならない.
English translation is not the literal meaning. だめ is not can't. It means 'no good'. So the teacher is basically saying "No, (using a dictionary is) no good."
It's weird to say that kind of sentence in English so we use the context and create a more natural translation, which is 'No you can't (use a dictionary)."
From i own experience in Japanese it is possible omit large parts of the sentence and still have a valid expression. In this way you can you say "いいえ、ダメです" (note: usually written in Katakana i think) in the context of you question would mean "No, you cannot use the dictionary"
Generally speaking, the longer the expression the more polity it is considered. So, a more polite way would be "辞書出来ませんですけれども。" Note that in this sentence ですけれども does not really have a meaning, but is used to make the expression more soft (often translated as "but").
Same is also true for English i think. "Can i use the dictionary?" Can be answered in multiple levels of politeness:
"No", "No, you cannot", "No you cannot use the dictionary", ...., "Unfortunately i am very sorry but it is not possible to use the dictionary"
The last option is something that would be used in a professional context i guess.