可控扩散叶型（ CDA）的优化设计是目前国外对亚音、跨音速压气机叶型研究的主要内容之一。

The optimum design of Controlled Diffusion Airfoils (CDA) is one of the main research fields in subsonic and transonic profile design for multistage compressor.

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一些科学家认为，这种林业害虫，不可避免地会借由加拿大北部针叶林带中的短叶松走廊，迅速向东扩散。

Some scientists say it is inevitable that the tree-killing insect will spread all the way east via a corridor of jack pines across northern Canada's boreal forest.

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上世纪后半叶，由于防治措施脱离现实，艾滋病在中国由传入期演变为扩散期，在高危人群中迅速蔓延。

In the second half, due to the prevention and control measures from the reality of AIDS in China from imported into a period of proliferation, the rapid spread of high-risk groups.

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