已知圆锥的母线长为15cm,底面直径为18cm,则圆锥的侧面积为()cm2(结果

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问题:

已知圆锥的母线长为15cm,底面直径为18cm,则圆锥的侧面积为(    )cm2(结果保留π)

考点:圆锥的计算
题型:填空题

The American economic system is organized around a basically private-enterprise, market-oriented economy in which consumers largely determine what shall be produced by spending their money in the marketplace for those goods and services that they want most. Private businessmen, striving to make profits, produce these goods and services in competition with other businessmen; and the profit motive, operating under competitive pressures, largely determines how these goods and services are produced. (47)Thus, in the American economic system it is the demand of individual consumers, coupled with the desire of businessmen to maximize profits and the desire of individuals to maximize their incomes that together determine what shall be produced and how resources are used to produce it.
(48)An important factor in a market-oriented economy is the mechanism by which consumer demands can be expressed and responded to by producers. In the American economy, this mechanism is provided by a price system, a process in which prices rise and fall in response to relative demands of consumers and supplies offered by seller-producers. If the product is in short supply relative to the demand, the price will be bid up and some consumers will be eliminated from the market. (49)If, on the other hand, producing more of a commodity results in reducing its cost, this will tend to increase the supply offered by seller-producers, which in turn will lower the price and permit more consumers to buy the product. Thus, price is the regulating mechanism in the American economic system.
The important factor in a private-enterprise economy is that individuals are allowed to own productive resources (private property), and they are permitted to hire labor, gain control over natural resources, and produce goods and services for sale at a profit. (50)In the American economy, the concept of private property embraces not only the ownership of productive resources but also certain rights, including the right to determine the price of a product or to make a free contract with another private individual.

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一般把国民经济划分为三大产业。下列各项中属于第二产业的是()。

A.采掘业

B.制造业

C.房地产业

D.建筑业

E.农业

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随机对照试验中的“双盲法”是指()

A.治疗组服用试验药物,对照组服用安慰剂

B.研究者和研究对象都不知道安慰剂的性质

C.研究者和研究对象都不知道药物的性质

D.研究者和研究对象都不知道分组情况

E.两组研究对象互相不认识

题型:填空题

下列各句没有语病的一项是(     )

A.船长的后面跟着一个粗野的汉子,气喘吁吁,衣服零乱,可是掩盖不住一种得意。

B.丹柯那种为理想献身、不计较个人得失的精神,以及坚定不移的态度和勇于献身的精神,鼓舞和感染着读者。

C.她母亲把她视为自身的一个残疾,如果与男孩相比较而言,母亲更把女儿视为自身的一部分。

D.在美国传统文学中,海明威的宗师是马克·吐温和他的《哈克贝利·费恩历险记》,直截了当和不拘陈规的叙述方式和节奏对他影响很大。

题型:填空题

在液态乳的卫生指标的规定中,原料乳的细菌总数不得超过()cfu/mL。

A.10

B.20

C.30

D.40

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