Here is a riddle:

"I am in minutes, months, and time, and time ITSELF, but never in a thousand years. What am I?"

The answer is "seconds".

NO

YES

To solve this riddle, we need to identify something that is present in "minutes," "months," and "time," yet absent in "a thousand years." Let's break it down:

The answer is something that can be found in "minutes." In minutes, we measure time and the answer is present. So, the answer must have a relationship with time.

The answer is also found in "months." On a calendar, we measure time in months, and again, the answer is present. This reinforces the idea that the answer has something to do with time.

The riddle further mentions that the answer is present in "time itself." This implies that the answer is a fundamental aspect or component of time.

The final clue states that the answer is absent in "a thousand years." This indicates that the answer does not exist or is not applicable at such a lengthy timescale.

Putting it all together, the answer to this riddle is the letter "M." It appears in the word "minutes," "months," and "time," but not in the phrase "a thousand years." Therefore, the letter "M" is the correct answer.