Example: She came after him. Method: Find the word that relates the noun to an other word. Answer: In the above sentence, the word 'after' tells us the relationship between 'She' and 'him'. Therefore, the answer is 'after'.
Example: I ____ apple.
like
likes
In the above sentence, the subject is "I" and it is singular. Therefore, the verb that goes with it must also be singular. Hence, "like" is the answer.