Answer:
Its - car
This - More and more physicians are beginning to look not just for illnesses but also for patients' habits with long-term health implications
Its - cow
Someone - no antecedent
It - antecedent not clear
Explanation:
The antecedent of a pronoun is the word or phrase whose place the pronoun takes. In some cases, the antecedent is obvious, while in others it's either missing or not clear.
In the first and third sentences, it's simple. In the first sentence, a car's transmission is mentioned. Instead of repeating the word <em>car</em>, we will use the pronoun<em> it</em> and its possessive form <em>its</em><em>.</em> It's the same in the third sentence (cow's tail - its tail).
The second example is interesting because the antecedent of the pronoun <em>this</em> is the entire previous sentence.
In the fourth sentence, the antecedent is missing. We don't know instead of what word the pronoun <em>someone</em> is used.
In the fifth, the antecedent is not clear as the pronoun <em>it </em>could be used to refer to the word <em>rain</em>, or the word <em>mud</em>.
