* 流程图，选自《剑桥雅思真题集12》
流程图类型：1)制造/制作(包括发电)工序;2)生命循环;3)业务办理。
每个步骤都不能错过。但是有没有main features呢?有。单个步骤中，设备多/复杂，或工艺复杂时，是main features。
Introduction
Shown in the diagram is using geological thermal energy to generate electric power. The whole process goes through a number of steps.
* 词汇补充：温度计thermometer，其中meter是“表”的意思。
Body
The first step is injecting cold water, which is stored in an above-ground tank, into the injection well, which has a depth of 4.5km / goes down to the depths of 4.5km. Then, the water goes through the geothermal zone – a layer of hot rocks, and reaches the production well, whose depth is identical to that of the injection well and whose width is greater. As the water goes through the hot rocks, it becomes hot water. After this step, hot water is pumped up and goes into the condenser, which is also situated above the ground. The condenser produces steam from the hot water, and as the steam reaches the turbine, the turbine spins. The spinning makes the generator work and produce electricity. At this point, electric power is transmitted by the towers and wires.
* 独立步骤不要用定语从句写。定语从句是补充说明。在流程图中，用来补充说明流程中的工具/器械/设备的特点。
* 难点在于动词。
* 不要把步骤拆分太细碎，以避免都是简单短句。
* 主语的多样性：流程的步骤(“步骤”这个词或具体步骤操作/行为)、流程的主体(水)、流程中的工具/器械/设备。
Conclusion
Overall, the entire process is moderately complex / of moderate complexity.
* 流程图的总述：整个流程是否复杂。
