The modem karst formation started in the old Tertiary Period, and matured in the Quatemary Period.

现代岩溶的形成开始于老第三纪，成熟于第四纪。

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This 65.5-million-year-old layer of Earth separates fossils of the Cretaceous period from those of the Tertiary period.

这个有着6550万年历史的地层分离了白垩纪的化石和第三纪的化石。

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As developing time continues, remnant resources become less and less and most ot old oil fields has entered into the tertiary oil recovery stage.

随着开采时间的延续，剩余资源量逐步减少，大多数老油气田已进入三次采油阶段。

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In the OECD 35% of the 25- to 34-year-old workforce has completed tertiary education, compared with 20% of the cohort approaching retirement.

ECONOMIST: Valuing education