身体前几个节间沟内经常无背孔。

There are usually no dorsal pores in the first few intersegmental grooves.

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无背衬的单面焊缝可评定有背衬的双面焊缝；

Welds made from one side without backing qualify welds made from both sides and welds with backing;

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本文的工作为无背索斜塔斜拉桥的设计提供了参考。

The conclusions of this paper offer reference for the design of no back-stays & inclined pylon cable-stayed bridge.

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