How to identify the problem when cranking the engine but the car can't start

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When cranking the engine the car seems to start, (e.g. engine sounds running) the RPM needle went up then slowly went down and die for 2,3 time then can't start any more Check all stuffs like fuel (of course full tank), battery, cable, spark plug, sensors and all seems OK as all we can do for now and feels hopeless and don't want to bring the car to dealer of special shop just yet and hope you guys can help by give us some hints, suggestions where, what etc.. we can check. Thanks in advance and much appreciated appreciated..