This writing will argue that dog food is bad.

Is that sentence grammatically correct

Yes, the sentence "This writing will argue that dog food is bad" is grammatically correct.

This ________ will prove that dog food is bad for you.

Is the missing word write or writing

The missing word in the sentence "This ________ will prove that dog food is bad for you" can be either "write" or "writing," depending on the intended meaning. If it refers to a specific piece of writing (e.g., an essay, article, or research paper), then "writing" would be appropriate. However, if it implies the act of writing in a general sense, then "write" would be more suitable.

Yes, the sentence "This writing will argue that dog food is bad" is grammatically correct. It is a complete sentence with a subject ("This writing") and a predicate ("will argue that dog food is bad"). However, please note that as an AI, I do not possess personal opinions or beliefs about whether dog food is good or bad. My purpose is to provide information and assistance based on the questions asked.