Final answer:
To identify the subject in the provided sentence, locate the 'be verb' and then determine who or what is associated with it. The subject is 'the biggest disadvantage of airplane travel,' which is singular and agrees with the singular verb 'is.' This showcases proper subject-verb agreement.
Step-by-step explanation:
To identify the subject in the sentence "Although very convenient, the biggest disadvantage of airplane travel is the exorbitant cost involved," you should first locate the verb. The verb in this sentence is 'is,' which is a be verb. Asking 'what is' helps you find that the subject is 'the biggest disadvantage of airplane travel.' It's important to ignore prepositional phrases and look directly before the verb to find the subject. This subject is a noun phrase.
Subjects are crucial for subject-verb agreement, and the verb should match in number (singular or plural) with the subject. In this example, the subject is singular, so the singular form of the verb 'is' is used.
In summary, when reviewing subject, verb, and adverbial elements, find the verb first and then determine 'who' or 'what' is associated with the verb to find the subject. Lastly, confirm that the subject and verb agree in number.