Let's analyze the given sentences and the highlighted words:

1. "True love is a great virtue." - Here, "love" is the subject of the sentence. It is a thing or an idea being described. Therefore, "love" is used as a noun.

2. "Parents love their children." - Here, "love" is an action performed by the subject (parents). It shows what the parents do. Therefore, "love" is used as a verb.

The same word "love" functions as different parts of speech based on its role in the sentence.

Final Answer: The highlighted words have been used as Noun; Verb.

Related Concepts

Noun: A noun is a word that names a person, place, thing, or idea. In the first sentence, "love" is the name of a concept or thing.

Verb: A verb is a word that expresses an action, occurrence, or state of being. In the second sentence, "love" is the action that the parents are doing.

Many words in English can function as different parts of speech (e.g., noun, verb, adjective) depending on how they are used in a sentence. This is a key concept in grammar.

Key Takeaway

Always look at the function of a word within its sentence to determine its part of speech. Do not memorize words as only one type.