Bicycles
自行车
When we are used to the cars running in the streets now, we may forget the life with bicycles. Tens of years ago, people used to go to work by bike. Bicycles are cheap and convenient. So many bicycles in the street used to be a great view. In fact, riding bicycles is a good exercise to keep healthy. And it helps to prevent the air pollution. We'd better ride bicycles as often as we can.
注释：
1）be used to 习惯于
2）tens of years ago 几十年前
3）used to go to work by bike（过去）常常骑自行车上班
4）used to be a great view（过去）常常是一大景观
5）prevent the air pollution 防止污染
6）as often as we can 尽可能经常地
在初中英语写作中，议论文和说明文是两种常见的文体。议论文主要是对某个问题或事件进行分析和评论，表达作者的观点、立场和看法；而说明文则是以客观的方式介绍或解释事物的性质、特征、功能等。
议论文：自行车的重要性
In today's fast-paced world, bicycles remain an essential mode of transportation for many people. Not only do they offer a healthy and environmentally friendly alternative to cars and motorbikes, but they also help reduce traffic congestion in urban areas. This essay will discuss the importance of bicycles in our daily lives.
在当今快节奏的世界中，自行车对于许多人来说仍然是一个重要的交通工具。它们不仅提供了一种健康且环保的替代方案，与汽车和摩托车相比，而且还有助于减少城市地区的交通拥堵。本文将讨论自行车在我们日常生活中的重要性。
Firstly, cycling is a great way to stay fit and healthy. It is a low-impact exercise that can be enjoyed by people of all ages and fitness levels. Regular cycling can improve cardiovascular health, strengthen muscles, and boost the immune system.
首先，骑自行车是保持健康的一种绝佳方式。这是一种低冲击力的运动，适合所有年龄和健康水平的人享受。定期骑自行车可以改善心血管健康，增强肌肉，并增强免疫系统。
Secondly, bicycles are an eco-friendly option. Unlike cars and motorbikes that emit harmful gases, bicycles produce no pollution. By choosing to cycle, we can all contribute to a cleaner and greener planet.
其次，自行车是一个环保的选择。与排放有害气体的汽车和摩托车不同，自行车不产生污染。通过选择骑自行车，我们都可以为一个更清洁、更绿色的地球做出贡献。
Lastly, bicycles can help alleviate traffic problems in cities. As more people opt to cycle, there will be fewer cars on the road, leading to less congestion and shorter travel times for everyone.
最后，自行车可以帮助缓解城市的交通问题。随着越来越多的人选择骑自行车，路上的汽车将会减少，这将导致交通拥堵减少，每个人的旅行时间缩短。
In conclusion, bicycles play a vital role in promoting health, protecting the environment, and improving urban transportation. We should all consider incorporating cycling into our daily routines to enjoy the numerous benefits it offers.
总之，自行车在促进健康、保护环境和改善城市交通方面发挥着至关重要的作用。我们都应该考虑将骑自行车纳入我们的日常生活，以享受它提供的诸多好处。
说明文：自行车的结构和功能
A bicycle is a two-wheeled vehicle that is powered by the rider's pedaling. It consists of several key components that work together to provide a smooth and efficient ride. This article will explain the structure and function of a typical bicycle.
自行车是一种双轮驱动的车辆，由骑行者踩踏踏板来驱动。它由几个关键部件组成，这些部件协同工作，提供平稳高效的骑行体验。本文将解释典型自行车的结构和功能。
The frame is the main structure of the bicycle, to which all other parts are attached. It is typically made of metal or carbon fiber and is designed to be lightweight yet strong.
车架是自行车的主要结构，所有其他部件都附着在上面。它通常由金属或碳纤维制成，旨在轻便而坚固。
The wheels are another crucial part of the bicycle, allowing it to move. Each wheel has a tire, a rim, and spokes. The tires provide grip and cushioning, while the spokes support the rim.
轮子是自行车的另一个关键部分，使它能够移动。每个轮子都有一个轮胎、一个轮辋和轮辐。轮胎提供抓地力和缓冲，而轮辐支撑轮辋。
The drivetrain includes the pedals, chain, and gears. The pedals are where the rider applies force to propel the bicycle forward. The chain transfers this force to the gears, which can be shifted to change the bicycle's speed and ease of pedaling.
传动系统包括踏板、链条和齿轮。踏板是骑行者施加力量推动自行车前进的地方。链条将这种力量传递给齿轮，可以变换齿轮来改变自行车的速度和踩踏的轻松程度。
The brakes are essential for controlling the bicycle's speed and stopping safely. They can be either hand-operated or foot-operated and work by applying pressure to the wheels to slow them down.
刹车对于控制自行车的速度和安全停止至关重要。它们可以是手操作或脚操作，通过向轮子施加压力来减慢它们的速度。
In addition to these components, bicycles often have a saddle for the rider's comfort, handlebars for steering, and a headlight for visibility in low light conditions.
除了这些部件，自行车通常还有一个鞍座供骑行者舒适乘坐，有把手用于转向，以及一个前灯用于在光线较暗的条件下提高可见性。
In summary, the bicycle is a simple yet effective means of transportation that combines human power with mechanical efficiency. Its various parts work in harmony to provide a reliable and enjoyable mode of travel.
总之，自行车是一种简单而有效的交通工具，它结合了人力和机械效率。它的各种部件和谐工作，提供了一种可靠且愉快的旅行方式。