The task question is indeed underexplained and specified: i'll try to correct this.
flight management task: collection of all discrete tasks, so tasks tha have a limited time span, e.g. doing the landing checklist
manual control task: the continuous task of manually flying the airplane. If the autopilot is used, this can be replaced by an intensive continuous monitoring task.
scanning and monitoring: continuous task of perception of information on the state of the aircraft. So scaaning is the acquisition of data and understanding it, while monitoring stands for the guarding-function of the pilot with respect to the aircraft-state.
ATC task: includes the obvious comm tasks and the less obvious tasks imposed by the consequences of ATC-dictated altitudes and speeds. Both discrete tasks and continuous tasks.