The United States is well-known for its network of major highways designed to help a driver get from one place to another in the shortest possible time．【C1】______these wide modern Roads are generally【C2】______and well maintained, with【C3】______sharp curves and many straight【C4】______, a direct route is not always the most【C5】______one．large highways often pass【C6】______scenic areas and interesting small towns．Further more, these highways generally【C7】______large centres which means that they become crowded with【C8】______traffic during rush hours,【C9】______the 'fast, direct' way becomes a very slow route.
However, there is【C10】______always another route to take【C11】______you are not in a hurry．Not far from the【C12】______new 'superhighways', there are often older,【C13】______heavily traveled roads which go through the countryside.【C14】______of these are good two-lane(双车道)roads; others are uneven roads【C15】______through the country．These secondary routes may go up steep slopes, along high【C16】______, or down frightening hillsides to towns【C17】______in deep valleys．Through these less direct routes, longer and slower, they generally go to places【C18】______the air is clean and the scenery(风景)is beautiful, and the driver may have a【C19】______to get a fresh, clean【C20】______of the world.
【C1】