1. He will come back in five days.
1-2. He will come back at the end of five days.
2. He will come back within five days.
3. He will come back after five days.
4. He came back after five days.
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Does #1 mean #1-1?
What about #3? I think #4 is right.
#2 means any time before five days has elapsed (could be one, three, five days - WITHIN five). At the end of five days means just that - five days will pass before he returns. In this case, "in" and "within" can be taken to mean something different. "In" means the whole five days. "After five days" means SOME TIME after five days have elapsed. Maybe the sixth day, the end of the fifth day, the seventh day? It implies that five is the minimum he will be away. Really, "in a day" implies the whole day while "within" means a part of the day in your earlier examples.
Can we use #3?
In the past tense, we can use 'after' as in #4? What about #3 in the future tense?
#s 3 and 4 are correct as they are written.
Let's break down each sentence to understand their meanings:
1. "He will come back in five days."
This sentence means that the person will return after a period of exactly five days. It does not necessarily imply the end of the five-day period.
1-2. "He will come back at the end of five days."
This sentence means that the person will return only when the full five-day period has elapsed. It implies the end of the five-day period.
2. "He will come back within five days."
This sentence means that the person will return at some point before the five-day period is over. It does not specify whether it will be right at the end or earlier.
3. "He will come back after five days."
This sentence means that the person will return only after the full five-day period has passed. It implies that the return will occur specifically after the five-day mark.
4. "He came back after five days."
This sentence states that the person returned after a period of five days has already passed. It indicates a past event and suggests that the five-day period is now complete.
To summarize, #1 does not necessarily mean #1-2, as it does not specify whether the return will occur at the end or sometime during the five-day period. #3 means a return specifically after the full five-day period. Finally, #4 states a past event where the person has already returned.