Level 5 - Unit 3 - Part 2 Listen

A flow chart, like this one, shows how a process begins and ends, and the steps in between. The process can be of almost any kind, from manufacturing a tire to creating an advertisement. Therefore, learning how to describe and explain a process in English is important. It's important for teachers, engineers, and people who provide customer support.
这副流程图演示了一个过程如何开始和结束，以及中间的步骤。从生产轮胎到制作广告，所有过程几乎都是如此，因此，学习如何用英语描述和解释过程是很重要的，这对教师、工程师和客户支持人员来说都很重要。

One process that we are all familiar with is our body's circulatory system. This system provides oxygen throughout the body and eliminates carbon dioxide, which is a waste product. If something goes wrong with this system, we need to repair it quickly, or we die. So it's important to understand it and keep it functioning properly.
我们都熟悉的一个过程是我们身体的循环系统，这个系统为全身提供氧气，排出二氧化碳——二氧化碳是一种废气。如果该系统出现问题，我们需要尽快修复，否则我们就会死亡，所以理解它并使其正常工作非常重要。

First, the most important requirement for the system to work is a supply of air. Without fresh air with sufficient oxygen, the process won't keep us healthy and alive. So the process begins by breathing in air, which happens when the lungs expand and draw in air. Once inside the lungs, oxygen in the air is exchanged for carbon dioxide in the blood. This exchange happens when blood cells release carbon dioxide and absorb oxygen. This blood is now oxygenated blood, which means it carries oxygen.
首先，该系统工作的最重要要求是空气的供应。如果没有含足够氧气的新鲜空气，那么这个过程就不能保持我们的健康和生命。所以这个过程从吸入空气开始，当肺部扩张吸入空气时就会发生。空气中的氧气一旦进入肺部，就会与血液中的二氧化碳交换。这种交换发生在血液细胞释放二氧化碳，吸收氧气的时候。这种血液现在是含氧血，这意味着它携带着氧气。

To summarize,the process begins by inhaling air and oxygenating the blood. The oxygenated blood in the lungs then flows back to the heart. The C02 which came from the blood is exhaled, and the next cycle begins.
总而言之，这个过程从吸入空气和给血液充氧开始，然后肺部的含氧血流回心脏，来自血液的二氧化碳被呼出，下一个循环开始。

Note that the blood in the lungs flows in a loop from the heart. The blood which enters the loop from the heart carries carbon dioxide. Once the carbon dioxide is exchanged for oxygen, the blood continues through the loop and exits into the heart. The oxygenated blood is then pumped to the rest of the body.
注意肺部的血液从心脏循环流动。来自心脏进入循环的血液携带着二氧化碳，一旦二氧化碳被转化为氧气，血液就会继续循环，流出心脏。含氧的血液被推送到身体的其他部位。