What are linking verbs?
Linking verbs are the words that give information about the subject, such as a relationship or a condition. In other words, these are the verbs connecting the subject to the predicate noun or adjective. Some examples of linking verbs include am, are, were, being, been, was, etc.
Is it correct- How old she is?
Yes, there is nothing wrong with this sentence- How old she is, however, only if it is without a question mark, as this sentence implies that the person is making a statement. If a person is asking a question, then this sentence is not correct. Although, it is correct to say- Can you guess how old she is?
What will be the correct sentence if I want to ask a question about the age of the third-person female?
If you want to ask a question, you can say- how old is she? Then the other person will let you know how old she is.