A number of different sub fields and specialty areas have emerged.

出现了许多不同的分支领域和专门领域。

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Although you could model all your data without attributes, they can be a very intuitive choice for data items which are known in advance to never repeat (per element) nor have any sub-fields.

虽然不用属性也可以对所有数据进行建模，但是对于预先知道不会重复(对于每个元素而言)，也没有任何子字段的数据项，使用属性仍是最直观的选择。

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In those fields, standard manufactured components, sub-assemblies, and reactions are bench tested.

在那些领域，标准化制造的部件、子系统集成和反作用，已经成为基准测试。

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Apart from the sub-salt fields, Petrobras is exploring 270 blocks in the Gulf of Mexico and over 200 more onshore in Brazil.

ECONOMIST: Brazil's Petrobras

Green aficionados are familiar with the statistic that the sun bathes the Earth in trillions of barrels of energy (in oil equivalent terms), and less familiar with the fact that total known hydrocarbon resources are also countable in the trillions of barrels (from the oil-sands and ultra-deep-water sub-salt fields, to methane hydrates and coal, not to mention shale gas).

FORBES: Steve Forbes Is Wrong

For example, researchers in Arizona are using real-time kinematic global positioning systems, an ultra-precise version of GPS that can measure positions with sub-inch accuracy levels, to control weeds in cotton fields with steel cultivators.

FORBES: American Agriculture's 'Sputnik Moment'