求翻译：首先，自行车便于携带，其次它也是一种运动，有利于锻炼身体，因为越野自行车的快与刺激，对自己也是个突破和挑战，最重要的是它比汽车节省能源，不污染大气，为环保做出了贡献是什么意思？

First, the bike easy to carry, and secondly it is a sport conducive to exercise, because the fast and exciting off-road bikes, but also a breakthrough of their own and challenges, the most important thing is to save energy than cars, do not pollute the atmosphere for environmental protection contrib

First of all, bicycle portability, followed by a movement, it is also conducive to physical activity, because mountain bikes with the fastest, to stimulate and challenge themselves, and it is also a breakthrough in the most important thing is that it is more than motor vehicle pollution of the atmos

First, the bicycle is advantageous for the carryhome, next it also is one kind of movement, is advantageous in exercising the body, because of the cross country bicycle with the stimulation, to oneself also is quickly a breakthrough and the challenge, most importantly it saves the energy compared to

First, the bike is easy to carry, and secondly it is also a movement, to exercise, because mountain bike fast and stimulating, on his own is a breakthrough and challenging, the most important thing is that it auto saves energy, do not pollute the atmosphere, contributing to the environmental protect

First, the bike easy to carry, and secondly it is a sport conducive to exercise, because the fast and exciting off-road bikes, but also a breakthrough of their own and challenges, the most important thing is to save energy than cars, do not pollute the atmosphere for environmental protection contrib