1. Technician A says that after testing or servicing the hydraulic system components, always check and refill the master cylinder. Technician B says that after testing or servicing the hydraulic components, always make sure the hydraulic system is free from air. Who is correct? OA. Technician A only OB. Technician B only OC. Both Technician A and B OD. Neither Teglhnician A nor B​

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]