题目

Labor force is defined as being the total number of people who are available to work and earn income. This definition includes everyone who is employed or seeking paid employment, so it includes employers and the self-employed. Labor is one of the country's resources which can be combined with other resources to produce the goods and services wanted by the community.        Although the size of the workforce depends a great deal on the size of the total population, there are several other influences which also affect it. The age distribution (分布) of the total population has a very ma实验室有下列四种量筒，分别标有最大量度和最小刻度，只能一次并能准确测出质量为100g密度为0.8 g/cm3的酒精应选用的量筒是 （ ）A. 250mL，5mL B. 500mL，10mL C. 100mL，2mL D. 50mL，2mL