double contraction

基本解释

To economists, a double-dip has a narrow meaning: a period when the economy comes out of recession only to suffer another contraction.
对于经济学家来说，“二次探底”的定义是很严格的：二次探底是指经济从衰退到复苏，再萎缩的时期。
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By anti-frozen performance, resistance to abrasion, contraction and resistance to fatigue and other durability tests to examining the mixture ratio of the double mineral composite powder concrete.
通过抗冻性、抗渗性、耐磨性、收缩性以及抗疲劳性等耐久性试验对研究中所确定的配合比进行检验，最终得出复合双掺矿质超细粉路面混凝土的最佳配合比。
The column uses the double expansion and contraction function hydraulic cylinder, increases the power stroke to satisfy the support to adjust the high scope the need.
立柱采用双伸缩作用液压缸，以增加工作行程来满足支架调高范围的需要。