1. I go to bed early on Saturdays.

2. I don't go to bed early on Saturdays.
3. I don't go to bed early every Saturday.
4. I sometimes go to bed on Saturday, and I sometimes don't go to bed on Saturday.
5. On Saturday, I never go to bed early.
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Are #2 and #3 the negative sentences of #1?
Does #3 mean #4? Does #2 mean #4?
Does #3 mean #5? Does #2 mean #5?
What is the exact meaning of #2 or #3 in negative sentences?

I wouldn't use #3, but #1 and #2 are opposites (or negatives) of each other.

#3 is not used, and #4 is VERY wordy. Since it's a "sometimes" idea, all you need is one half of that sentence or the other, but not both. Also, the word "sometimes" needs to be at the beginning of the sentence, not between the subject and verb.

#5 is well phrased. This is a really good opposite for #1.

#5 is correct

To determine the exact meaning of sentences, it is important to understand their structure and the words used. Let's break down each sentence to determine their meanings:

1. "I go to bed early on Saturdays."
This sentence indicates that the speaker has a regular habit of going to bed early on Saturdays.

2. "I don't go to bed early on Saturdays."
This sentence is a negation of sentence 1. It means that the speaker does not have the habit of going to bed early on Saturdays.

3. "I don't go to bed early every Saturday."
This sentence suggests that the speaker does not go to bed early on some Saturdays but does so on others. It indicates a lack of consistency in bedtime habits on Saturdays.

4. "I sometimes go to bed on Saturday, and I sometimes don't go to bed on Saturday."
This sentence reinforces the idea that there is inconsistency in the speaker's bedtime habits on Saturdays. It states that occasionally the speaker goes to bed, and occasionally they do not.

5. "On Saturday, I never go to bed early."
This sentence expressly states that the speaker does not go to bed early on Saturdays; it is a habitual behavior to stay up late on Saturdays.

To answer your specific questions:
- No, sentence 2 is not the negative sentence of sentence 1. Sentence 2 negates the entire statement whereas sentence 1 is an affirmative statement.
- Sentence 3 does not have the exact meaning of sentence 4. While both sentences suggest inconsistency in bedtime habits on Saturdays, sentence 3 implies occasional late nights and occasional early bedtimes, whereas sentence 4 only states that the speaker sometimes goes to bed on Saturdays and sometimes does not.
- Sentence 3 does not mean sentence 5. Sentence 3 implies occasional late nights, but it does not explicitly state never going to bed early on Saturdays like sentence 5 does.
- Sentence 2 also does not mean sentence 5. Sentence 2 simply negates the statement that the speaker goes to bed early on Saturdays; it does not express anything about staying up late.

In conclusion, sentences 2 and 3 have different meanings. Sentence 2 indicates that the speaker does not have the habit of going to bed early on Saturdays, while sentence 3 suggests an inconsistent bedtime routine on Saturdays, with both early and late nights occurring occasionally.