Just a sample

Makefile

taskA:
	@echo "this is task A"
	@sleep 1
	@echo "end task A"

taskB: taskA
	@echo "this is task B"
	@sleep 3
	@echo "end task B"

taskC: taskA
	@echo "this is task C"
	@sleep 2
	@echo "end task C"

taskD: taskC
	@echo "this is task D"
	@sleep 4
	@echo "end task D"

taskE: taskB taskD
	@echo "this is task E"