By
Part of speech: adverb
Definition: Along a path which runs by the speaker.
Part of speech: noun
Definition: A pass
Part of speech: adjective
Definition: Out of the way, subsidiary.
Part of speech: preposition
Definition: Near or next to. At some time before (the given time), or before the end of a given time interval. Through the action or presence of. (Indicates the creator of a work) Existing through the authorship etc of. (Indicates the cause of a condition or event) Through the action of, caused by, responsibility for; by dint of. (Indicates a means) Involving/using the means of. (Indicates a rule followed) Using the rules or logic of. (Indicates the amount of some progression) With a change of. (In the formulae X by X and by Xs, indicates a steady progression, one X after another.) (Indicates an oath) With the authority of. Used to separate dimensions when describing the size of something.
Part of speech: interjection
Definition: Goodbye.
Past
Part of speech: adverb
Definition: in a direction that passes
Part of speech: preposition
Definition: beyond in place, quantity or time
Part of speech: noun
Definition: The period of time that has already happened, in contrast to the present and the future.The past tense.
Part of speech: adjective
Definition: Having already happened; in the past; finished.Relating to the past.(of a period of time) the one before this one
Example sentence: Change is the law of life. And those who look only to the past or present are certain to miss the future.