操作翻矸机支承与（）手柄，由于翻矸机动作时，（）关闭，故（）不能动作。
A.翻转
B.阻车器
C.推车机
D.翻矸机
参考答案：A, B, C
Which of the following situations is least likely to lead to high barriers to entry and monopoly supply（）
A. Natural resources are spread among many firms.
B. Governmental licensing and regulations are present.
C. Economies of scale are present.
( )是正常经费按人员定额核定，专项经费根据需要和可能逐项核定。
A．复式预算
B．增量预算
C．单式预算
D．零基预算
