Happiness is the key to success.
This sentence contains two abstract nouns, happiness and success. Abstract nouns are usually ideas. A good way to check and see if a noun is abstract is to ask yourself 'would I be able to touch this?'. Since you can't touch happiness or success, they are abstract nouns. Keyboard is an abstract noun, because you can touch a keyboard.
Neither money nor fame will make you happy.
In this sentence, the correlative conjunction is neither...nor. Correlative conjunctions are conjunctions that contain more than one word or phrase. Another example of a correlative conjunction is both...and, as in 'Both Mary and I went to the store'.
Knowledge is power.
In this sentence, the linking verb is 'is'. Linking verbs connect the subject and predicate without indicating action. They usually describe a noun as being a noun or adjective. For instance, in this sentence, the linking verb 'is' is telling us that knowledge, a noun, is power, another noun. Some sentences containing linking verbs may describe a noun as being an adjective. For instance, in the sentence 'Apples are delicious', the linking verb 'are' is telling us that apples, a noun, are delicious, an adjective.
Hope this helps!
