Front assembly and pump

The utility model provides a preposed assembly and a pump, the preposed assembly is configured on a liquid inlet line of the pump, and the preposed assembly comprises a container for providing an accommodating space for accommodating liquid; the first pipeline is used for providing a passage between the liquid inlet of the container and a first solution, and the first solution is a pumping object source of the pump; the second pipeline provides a passage between the liquid outlet of the container and the liquid inlet of the pump; the first end of the second pipeline is arranged in the container through the liquid outlet of the container and is lower than the liquid inlet of the container; the volume between the liquid inlet of the container and the first end of the second pipeline is greater than or equal to the volume between the liquid inlet of the container and the liquid level of the first solution in the first pipeline; and when the pump works, the other parts of the container except for the joint of the