节育过程，妇女节育环取下的过程称下环。
band ; lower ring ; bottom ring ; bend
下环“库平七钱二分” “光绪元宝”四个字，字体俊秀。
Ring "library flat seven binary money" under the "wing" four word, font.
基于该定义，给出了Q2攻击结构下环上积性MSP的有效构造。
Then, based on this definition, an efficient construction of the multiplicative MSP for a Q2 adversary structure is given.
为了说明平衡现象，让我们看一下环丁烯异构成1．3一丁二烯的反应。
To illustrate some of the features of the equilibrium phenomenon, let us look at the reaction in which cyclobutene is isomerized to 1.3-butadiene.
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