Decide which of the choices given below would correctly complete the passage if inserted in the corresponding blanks. Mark the correct choice for each blank on your ANSWER SHEET.?

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. ___1these 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 ___7traffic 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, ___11heavily 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. collectD. 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。