参考答案:N 答案解析:从第六段中间“Most of any city’s population is engaged in providing goods and services for the city itself”
第18题: [单项选择]下列对提高胸壁胸膜病变的检出率无帮助的是() A. 重点在肋间扫查 B. 探头的选用根据病变位置而定 C. 根据X线胸片或CT的提示,选择重点扫查部位 D. 观察呼吸运动时对病灶显示的影响 E. 通过锁骨上、剑突下及肝、脾等超声窗显示病变 参考答案:E 答案解析:胸壁胸膜病变的检出主要在肋间扫查,通过锁骨上、剑突下及肝、脾等超声窗显示的是横膈和邻近肺底的病变。
第24题: [填空题]S1S9 参考答案:but it was a hundred years before Thomas Edison moved from theory and experiment to practical application. 答案解析:Main Points:but Thomas Edison put theory and experiment to practice a hundred years ago.