Is this sentence a declarative or interrogative?

"I wonder if all mammals have fur"

Declarative. It "declares" that the speaker wonders (questions).

To determine whether a sentence is declarative or interrogative, we need to consider its form and function.

In this case, the sentence "I wonder if all mammals have fur" is an interrogative sentence. It asks a question and seeks information. We can identify this as an interrogative sentence because it begins with the question word "if" and ends with a question mark.

To determine this on your own, you can follow these steps:
1. Read the sentence to understand its meaning.
2. Look for question words such as "who," "what," "when," "where," "why," and "how." These words often indicate interrogative sentences.
3. Pay attention to the sentence structure. Interrogative sentences generally have a subject-verb inversion (inverting the order of the subject and verb) or include a helping verb before the subject.
4. Note if the sentence ends with a question mark. This punctuation is usually a clear indicator of an interrogative sentence.