1. Explain: When the ideal gas passes through the adiabatic throttling process, how does its pressure (p), temperature (T), specific volume (v), internal energy (u) and enthalpy (h) of the ideal gas change? And tell the reasons briefly. Tips: u and h of ideal gas are both the sinle function of temperature. u-(T), h-f(T) 2. Judge and Explain: If the gas expands, then it must output work? Please give example.