1. It's because Chuchu felt that his old master was near.

2. It's because Chuchu felt that his old master was near to him.

3. It's because Chuchu felt that his old master was close to him.

4. It's because Chuchu felt that his old master was near him.

5. It's because Chuchu felt that his old master was so near him.

6. It's because Chuchu felt that his old master was so near to him.
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Are the sentences all grammatical? At the end of each sentence, there are changes.

Sentences 1-4 are fine.

Sentences 5 and 6 need to be completed. The word "so" here indicates that there's a "that..." clause expected.

... was so near that Chuchu could smell him.
(or some way to complete the thought that "so" begins)

Yes, all of the sentences are grammatically correct. However, at the end of each sentence, there are changes in terms of word choices and phrasing, which can slightly alter the meaning or emphasize certain aspects of the statement. Let's break down the changes in each sentence:

1. "near" - This is a simple statement indicating proximity.

2. "near to him" - The addition of "to him" emphasizes that the master is near Chuchu specifically.

3. "close to him" - The word "close" is used instead of "near," conveying a sense of proximity but with a slightly stronger emphasis on the closeness.

4. "near him" - This is similar to sentence 1, but "him" is used instead of "to him."

5. "so near him" - The addition of "so" suggests a greater degree of closeness, emphasizing the master's proximity.

6. "so near to him" - This is similar to sentence 5, but "to him" is used instead of "him."

So, while the sentences are grammatically correct, the variations demonstrate how slight changes in word choices and phrasing can convey different nuances or emphasize different aspects of the statement.