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. ___1___ these wide modern roads are generally ___2___ and well maintained, with___3___ sharp curves and straight sections, a direct route is not always the most ___4___ one. Large highways often pass ___5___ scenic areas and interesting small towns. Furthermore, these highways generally ___6___ large urban centers, which means that they become crowded with ___7___ traffic during rush hours, ___8___ the fast, direct route becomes a very slow route. However, there is almost always another route to take ___9___ you are not in a hurry. Not far from the ___10___ new superhighways , there are often older, ___11___ heavily traveled roads which go through the countryside. ___12___ of these are good two-lane roads; others are uneven roads curving through the country. These secondary routes may go up steep slopes, along high ___13___ , or down frightening hillside to towns ___14___ in deep valleys. Through these less direct routes, longer and slower, they generally go to places ___15___ the air is clean and scenery is beautiful, and the driver may have a chance to get a fresh, clean view of the world.
1. A. Although B. Since C. Because D. Therefore
2. A. stable B. splendid C. smooth D. complicated
3. A. little B. few C. much D. many
4. A. terrible B. possible C. enjoyable D. profitable
5. A. to B. into C. over D. by
6. A. lead B. connect C. collect D. communicate
7. A. large B. fast C. high D. heavy
8. A. when B. for C. but D. that
9. A. unless B. if C. as D. since
10. A. relatively B. regularly C. respectively D. reasonably
11. A. and B. less C. more D. or
12. A. All B. Several C. Lots D. Some
13. A. rocks B. cliffs C. roads D. paths
14. A. lying B. laying C. laid D. lied
15. A. there B. when C. which D. where
答案与解析：
1. A) 此空四个选项都是从属连词，但是它们的属性是不同的，例如：although是表示转折关系的;since，because，therefore是表示原因关系的。通过阅读此空所在句得知大概句义为： 尽管这些宽阔的现代化公路通常很平坦且维护良好，转弯也很少，但是一直保持笔直的公路不总是令人赏心悦目 。根据语义线索和语法线索可知此空应填表示转折关系的选项A。
2. C) 根据词汇线索和词义搭配可知，stable，splendid和complicated一般不能用来修饰roads。
3. B)根据语义线索可推断此空正确答案为选项B few。
4. C) 根据上下文可推测出如果高速公路总是保持笔直，对于驾驶者来说是非常枯燥的，因此本空的正确答案为C enjoyable。
5. D) 介词by能和动词pass搭配，意为 经过，掠过 。
6. B) 本句中的联系副词Furthermore说明本句是对上一句的进一步补充和信息的增加，由此可推测本句句义为高速公路不仅经过风景区和乡村，通常还 将庞大的都市中心区连接起来 。故正确答案为B。
7. D) 交通拥挤 用heavy 和traffic搭配。
8. A)通过分析可知，这里使用的是一个非限定性定语从句，四个选项中只有A when 具备此语法功能。
9. B)根据上下句关系可推断此句为条件句，故选项B为正确答案。
10. A)根据主句中的 older ... roads 可推断此空需要填一个比较意义的副词，以构成对比关系，故选项A relatively 相应地，相对地 为正确答案。其他三词词义分别为：regularly 有规律地，定期地 ;respectively 各自地 ;reasonably 有理由地 。
11. B)根据此空前后词及结构可断定此空应使用比较级，故可排除A和D。另外根据上下文可推测此空应为less，因为 more heavily traveled 意为 车辆拥挤的 公路，与常识不符。
12. D)从下文的others可知此空正确答案为D some。
13. B)根据上文的slopes和下文的hillsides就可以断定这里需要一个表示路况不好的词，选项A rocks意义不符，故只有B cliffs 悬崖 为正确答案。
14. A)根据题目和选项可断定此空应为towns的后置定语，由此可猜测句义为 位于深谷中的城镇 ， 位于 lie是不及物动词，不能以过去分词的形式出现作名词的后置修饰语，故正确答案为lie的现在分词形式lying。
15. D)定语从句修饰places用where来引导。