Cost
Part of speech: noun
Definition: Amount of money, time, etc. that is required or used. A negative consequence or loss that occurs or is required to occur.
Part of speech: verb
Definition: To incur a charge, a price. To calculate or estimate a value.
Example sentence: Once you got a solar panel on a roof, energy is free. Once we convert our entire electricity grid to green and renewable energy, cost of living goes down.
Be
Part of speech: verb
Definition: To occupy a place.To occur, to take place.To exist.elliptical form of for "be here", "go to and return from" or similar.Used to indicate that the subject and object are the same.Used to indicate that the values on either side of an equation are the same.Used to indicate that the subject plays the role of the predicate nominal.Used to connect a noun to an adjective that describes it.Used to indicate that the subject has the qualities described by a noun or noun phrase.Used to form the passive voice.Used to form the continuous forms of various tenses.Used to form the perfect aspect with certain intransitive verbs. Often still used for to goUsed to form future tenses, especially the future subjunctive.Used to indicate age.Used to indicate height.Used to indicate time of day, day of the week, or date.With since, used to indicate passage of time since the occurrence of an event.Used to indicate weather, air quality, or the like.Used to indicate temperature.