The United States is well-known for its 【C1】______of major higher highways designed to hel

The United States is well-known for its 【C1】______ of major higher highways designed to help a 【C2】______ get from one place to another in the shortest possible time. 【C3】______ these wide modern roads are generally 【C4】______ and well maintained, with much sharp curves and many straight 【C5】______ , a direct route is not always the most 【C6】______ one. Large 【C7】______ often pass by scenic areas and interesting small towns.

Furthermore, these highways generally 【C8】______ large urban centers, which means that they become crowded with 【C9】______ traffic during rush hours, 【C10】______ the " fast, direct" route becomes a very slow route. However, there is still 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. All of these are good two-lane roads; others are uneven roads 【C14】______ through the country. These secondary routes may 【C15】______ 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 is beautiful, and the driver may have a 【C19】______ to get a fresh, clean 【C20】______ of the world.

【C1】

A．network

B．equipment

C．facilities

D．way