1, representing length unit: meter. This is the abbreviation of British rice (or rice).

2. Representative time unit: minutes. This is the abbreviation of English Minute.

3 stands for one thousandth: milli. This is the abbreviation of English milli, which is usually added before the unit, and the value is one thousandth of the current unit. For example, mg: mg; mm:mm； Millisecond: Millisecond.

4. Represents constants, especially integer constants, such as A, B, C, K, N. ..