"did not come": 没来 vs 没来了 I translated "The student did not come" as "学生没来了" but the answer was "学生没来" (i.e. 了 is omitted). This answer confuses me because it doesn't contain any indication of past action; i.e. I would translate "The student is not coming" to "学生没来". 


Why is it that "了" is not required in this case?
Is my answer acceptable? What is the difference?
How would you distinguish "The student did not come" with "The student is not coming" in Chinese?
We don't say 学生没来了. I think it's because 没 itself has already addressed the tense. 学生没(有)来 is The fact of students coming is non-existent, namely Students didn't come or Students haven't come. So, we don't need 了 and 学生没来 just does the trick. 

However, when you use 不 for negation, either 学生不来 or 学生不来了 is correct but with different meanings. 学生不来 implies that students refused to come, 学生不来了 students won't come(the reason is unaddressed, it's factual rather than subjective/emotional).

Note: To translate "The student did not come", we should consider the context you put the sentence into. It could be simply 学生没来. But it's worth noting that Chinese isn't necessary to embrace the tense in a sentence and sometimes the tense is implied. We usually deduce the tense according to contexts.