Final answer:
In the SI system, three base quantities besides mass and length are time (second), electric current (ampere), and temperature (kelvin).
Step-by-step explanation:
Apart from the SI base units of mass (kilogram) and length (meter), three other base quantities in the SI system include time, electric current, and temperature.
The unit of time is the second (s), the unit of electric current is the ampere (A), and the unit for temperature is the kelvin (K). These units are part of the metric system of units, which means their values can be scaled by factors of 10 using metric prefixes to suit various applications.