1. He wants to really experience it. ['Really' modifies 'experience'.]

2. He really wants to experience it.
3. He wants really to experience it.
4. He wants to experience it really.
5. Really he wants to exprerience it.
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What is the right position of 'really'?
What about #3? In #3, what does 'really' modify? Is the word order natural? What about the others?

"really" modifies "wants", not "experience". #2 is best.

The natural position of the adverb "really" depends on the intended meaning and emphasis in the sentence. Let's analyze each of the given sentences:

1. "He wants to really experience it."
In this sentence, "really" modifies the verb "experience." The intended meaning is that he wants to truly or genuinely experience it.

2. "He really wants to experience it."
Here, "really" modifies the verb "wants." The emphasis is on the intensity of his desire to experience it.

3. "He wants really to experience it."
In this sentence, "really" is placed before the infinitive marker "to" and modifies the verb "wants." This word order is less common in English, and it can sound slightly unnatural. However, it is grammatically correct.

4. "He wants to experience it really."
Similarly to the first sentence, "really" modifies the verb "experience." The emphasis here is also on the genuine or true nature of the experience.

5. "Really he wants to experience it."
Here, "really" is placed at the beginning of the sentence for added emphasis. Its exact function is not clearly defined, as it does not have a direct word it modifies. Instead, it creates a general emphasis on the entire statement.

In summary, the most natural positions for "really" in these sentences are #1, #2, and #4, where it either modifies the verb "experience" or "wants" for emphasis. The word order in sentence #3 is grammatically correct but less commonly used. Sentence #5 is less common as well, and the function of "really" is for general emphasis rather than modifying a specific word.