Grammatical categories:
The grammatical categories of the words in the sentence are as follows:
Happy to constantly sing:
- Happy: adjective
- From: preposition.
- Sing: verb.
- Constantly: adverb.
Therefore, in the sentence we find the following grammatical categories: adjective, preposition, verb and adverb.
Adjectives are words that modify nouns. These have the same gender and number as the noun they modify.
Adverbs are the words that modify a verb, an adjective or another adverb. They are invariable words because they cannot change gender and number.
Verbs are actions, states and processes. Conjugated verbs have mood, tense, person, and number.
And prepositions are invariable words that link words.
¡Hope this helped!