7.2.3 First Law of Thermodynamics(热力学第一定律) 系统- system 环境- surroundings 边界- boundary Suirroundings Boundary Sy stem tried m>s) FIGURE 7. 2 51 Thermodynamic system7.2.3 First Law of Thermodynamics（热力学第一定律） 系统－system 环境-surroundings 边界-boundary