A time as short as almost zero is called an instant, and an instant is time. Time and time are different. For example, when did the event happen? How long did the incident last? These are two different concepts. We should distinguish the concepts of the last few seconds, the beginning of the last few seconds, the end of the second and the beginning of the second, and the concepts of the seconds, seconds and seconds after the first few seconds. Time and time are described by an infinite line, and the arrow of the line only indicates the order, not the direction. This line with an arrow is called the time axis. Each point on the time axis represents a moment. Time is a measure of the movement order of all substances. It has no length, only a sequence, which is an ordinal number. The interval length between two corresponding moments on the time axis represents a period of time, which is a physical quantity with only length and no direction. Time is continuous, one-way and sequential, and it always moves forward.

Moment can be used as a noun in writing, such as exciting moment. In addition, moment can also be used as an adverb to describe verbs, such as always being ready.