Negative matter is a hypothetical form of matter whose mass is opposite in sign to normal positive matter.

负质量是一种假象的物质形式，其质量在标示上与正常的正质量相反。

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Quantum chemical calculations of gossypol and thymine reveal that the net electronic charge distributions along the boldfaced line of their structural formula (Fig. 2) are just opposite in sign.

量子化学计算棉酚与胸腺嘧啶分子中的净电荷分布，发现沿两者结构式粗线上各原子的电荷恰好符号相反（图2）。

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The new moon takes place in your opposite sign of Libra on the 15th.

15日新月会出现在天秤座的对面。

《柯林斯英汉双解大词典》

sa So we have 1 s a, and we're drawing this as having a positive amplitude, but since we have destructive interference we're going to draw 1 s b as having the opposite sign, so we have a plus and a minus in terms of signs.

我们有，我们把这画成一个正的振幅，但因为我们是相消干涉,我们把1sb画成相反的符号，所以我们有一正一负两个符号。

麻省理工公开课 - 化学原理课程节选

" In the stands opposite the Toronto bench, three female fans held up a sign that read, "Send Boston Love.

NPR: Celtics Back On Court, Offer Tribute To Victims