The functions of the spleen include ( ). A: the site of generating immune responses B: filtration C: blood bank D: Involvement in lymphocyte recirculation

Large marine diesel engines of crosshead construction generally have two systems of lubrication: a total loss system feeding the （） and a recirculation system lubricating the running gear and cooling the piston.

The coolant flow through the core is generally greater than the coolant flow provided by the main pump, which is due to the existence of () A: Recirculation pump B: Condensate pump C: Steam turbine D: Feedwater heater