"I don't have a bag."

Translation: 我没有袋子。

[Patrick_Dark]

"我沒有一個袋子。" was rejected, but seems like a reasonable translation especially in light of the "請給我一個袋子。" exercise at https://www.duolingo.com/comment/25473940.

[nitedemon]

When you say "I dont have a bag", you are really saying is "I dont have ANY bags". In Chinese for these situations, since you are referring to the lack of that certain thing in general, instead of the lack of one thing, you don't need 一個 .

Unless you want to emphasis (I dont even have ONE bag), then it is 我一個袋子都没有。

[NasuSamaruk0]

I do not see the issue with the sentence Cloud_Kupo suggests. The meaning is still correct in either way - with or without 一個.

[baker3060]

How do you know when to add the 子? Sometimes I see 袋 and sometimes 袋子. What is the difference?

[George792719]

A classic example on inconsistency in this course. Only one or two questions back we needed to use 一个 to denote 'one' apple in a bag.

Here when you want 'one' bag they don't add the 一个.

Result? You are not sure when to use 一个 or not.

[Mitchelli13]

My implication is you use it when "one" is important. Buying one bag of apples is needing to say I just want one. "袋子" is used when saying you want a bag for the items just purchased, so the number isn't indeterminate, if you have three items that fit in one bag, that's implied to be one bag.
Hope that makes sense

[IanMcFarla17]

There appears to be no rhyme or reason with respect to whether 一个 is accepted or required in these sentences. In this very same lesson we have "Please give me a bag," and there the 一个 is required.