【单选题】It is commonly argued that national defense is a public good. Nevertheless, the weapons used by the U.S. military are produced by private firms. We can conclude that
A.
resources would be used more efficiently if the government produced the weapons.
B.
resources would be used more efficiently if private firms provided national defense.
C.
weapons are rival in consumption and excludable, but national defense is not rival in consumption and not excludable.
D.
national defense is rival in consumption and excludable, but weapons are not rival in consumption and not excludable.
【单选题】关于小儿呼吸功能特点,以下哪项不正确( )
【单选题】红外鉴别制备样品时,实验室相对湿度应小于( )
【单选题】The national plant of New Zealand is the ______.
【单选题】In 1995 Martin Luther King, Jr. gained national ______ for his nonviolent methods used in a bus boycott in Montgomery.
【单选题】一般情况下,企业提供产品的平均收益若低于以下哪种成本就停止营业( )
【单选题】The experts must have used big data to make the national economies predictable. Without thehelp of big data, the ranking would be ()(不能预言的).
【单选题】Every minute is made good ______ of ______ for the coming national examinations.
【单选题】关于液压传动的特点,下列说法错误的是( )