Turbofan engine...TSFC vs Mach Number...10 points ASAP!!!?

I have the Thrust Specific Fuel consumption plot for a turbofan engine versus the Mach Number. Until Mach = 1, the TSFC increases steadily for different flight altitude conditions (0 km...10 km, with the 0 km line on top and then 2km, 4 km etc). Can anyone tell me why TSFC increases with the Mach Number? I have also noticed that the fuel flow decreases with Mach Number. Why is that? And Why does Net thrust decrease with Mach number 0 km...10 km, with the 0 km line on top and then 2km, 4 km etc)? I am thankful for any help on this.