Here's a breakdown:
1. Coordinating Nouns and Pronouns:
* Usually awkward: Mixing nouns and pronouns can be clumsy and confusing. For example: "The dog and I went for a walk." This is fine if "I" is the subject of the sentence, but it can be better to say: "The dog and I went for a walk." Using "I" as the subject clarifies that both the dog and the speaker are going for a walk.
* Exceptions: In some cases, mixing nouns and pronouns can be acceptable and even necessary. For instance: "The dog and I went for a walk, but it was too hot for him." This is clear because "it" refers to the heat, not the dog, and "him" refers to the dog.
2. Coordinating Proper Nouns and Personal Pronouns:
* Usually awkward: Mixing proper nouns and personal pronouns can be confusing. For example: "John and I went to the store, but he forgot to buy milk." This sentence can be interpreted as "he" referring to either John or the speaker. It's clearer to say: "John and I went to the store, but I forgot to buy milk."
* Exceptions: As with general nouns, specific situations can justify this mixing. "John and I went to the store, but he was the one who forgot to buy milk." In this case, "he" clearly refers to John.
3. Key Considerations:
* Clarity: The primary goal in coordination is clear communication. If mixing nouns and pronouns creates ambiguity, it's best to rephrase for clarity.
* Formal vs. Informal: In formal writing, it's generally preferred to use consistent noun forms when coordinating. Informal writing might be more flexible.
In conclusion, it's not an absolute rule that nouns, proper nouns, and pronouns cannot be mixed in coordination. However, it's often advisable to avoid this mixing for clarity and avoid potential grammatical awkwardness.