单项选择题

He began working with balloons______.

A．as a relaxation from his work on aircraft
B．as part of his job at the time
C．as a hobby
D．when he heard that some Americans had crossed the Atlantic in one

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热门试题

单项选择题

What determines the price of a good in a market economy

A．The cost of all elements in production.
B．The cost of not making other goods.
C．The efficiency of the manufacturing process.
D．The quantity of materials supplied.

单项选择题

According to the passage, what is the relationship between production and resources

A．Available resources stimulate production.
B．Resources are totally independent of production.
C．Production increases as resources increase.
D．Production lessens the amount of available resources.