[单项选择] 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. 【B1】 these wide modem roads are generally 【B2】 and well maintained, with 【B3】 sharp curves and many straight 【B4】 , a direct route is not always the most 【B5】 one. Large highways often pass 【B6】 scenic areas and interesting small towns, Furthermore, these highways generally 【B7】 large urban centers, which means that they become crowded with 【B8】 traffic during rush hours, 【B9】 the "fast, direct" route becomes a very slow mute. However, there is 【B10】 always another route to take 【B11】 you are not in a hurry. Not far from the 【B12】 new "superhighways’’, there are often older, 【B13】 heavily traveled roads which go through the countryside. 【B14】 of these are good two-lane roads; others are uneven roads 【B15】 through the country. These secondary routes may go up steep slopes, along high 【B16】 , or down frightening hillsides to town
A. Although
B. Since
C. Because
D. Therefore