Sulfur has occasionally been found in the earth in an almost pure state.
A. regularly
B. accidentally
C. sometimes
D. successfully
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下列公式错误的是( )。
A. 总供给=消费十收入
B. 均衡国民收入=消费+储蓄
C. 总供给=消费+储蓄
D. 均衡国民收入=消费十投资
The most pressing problem any economic system faces is how to use its scarce resources.
A. puzzling
B. difficult
C. terrifying
D. urgent
Sally likes to tease her brother about his girl friends.
A. charm
B. laugh at
C. criticize
D. respect
由企业购买任何生产要素所发生的成本是指( )
A. 显性成本
B. 隐性成本
C. 机会成本
D. 总成本