The Editor’s Manual
Free learning resource on English grammar, punctuation, usage, and style.
Prepositions express relations of time (“during the day”) and space (“at the market”), and other abstract relations (“the secret of happiness”) between two parts of a sentence.
An infinitive is the basic form of a verb. It is generally used with the word “to” (“to run”). It can function as a noun, an adjective, or an adverb in a sentence.