The diagram illustrates the generation of electricity in a plant that uses hydraulic power. 总述时就说流程复杂还是简单： Overall, the production is hardly a complex process but rather simple, as it goes through a few steps and equipment.
The whole production follows a day-and-night cycle. 条线清晰、条理清楚、读者最喜欢的行文结构 就是 “总—分”结构没错了Water of the river is collected in the high-level reservoir created by the dam. During the day, water flows through the intake and via a tube down to the apparatus that has reversible turbines, whose spinning drives the generator at the power station. As the generator is turned on, it works to produce electric power, which is transmitted via the power lines to the national grid that delivers electricity to households. The water meanwhile goes to the low-level reservoir and is stored.
这里分段，吻合我们一开始确定下来的a day-and-night cycle这个逻辑。
During the night time, water in the low-level reservoir is pumped back by the reversible turbines and goes through the same route. It is stopped at the intake, which is closed at night, and waits until the next day for water from the high-level reservoir.