[单选题]带电高处作业应使用绝缘工具或穿()。
A.绝缘服
B.均压服
C.抗静电服
D.棉布衣物

Changes in the volume of unemployment are governed by three fundamental forces: the growth of the labor force, the increase in output per man-hour, and the growth of total demand for goods and services. Changes in the average hours of work enter in exactly parallel fashion but have been quantitatively less significant. As productivity rises, less labor is required per dollar of national product, or more goods and services can be produced with the same number of goods. If output does not grow, employment will certainly fall; if production increases more rapidly than productivity (less any decline in average hours worked)employment must rise. But the labor force grows, too. Unless gross national product( total final expenditure for goods and services corrected for price changes) rises more rapidly than the sum of productivity increase and labor force growth (again modified for any change in hours of work), the increase in employment will be inadequate to absorb the growth in the la
A. advocate a carefully managed economy
B. prefer the employment rate to rise and fall with the value of the gross national product as a check on labor costs
C. perceive high unemployment as undesirable but unavoidable
D. contend that manipulation of the size of the labor force would have prevented recessions in the years noted