Robert Recorde, The designer ofwel the equals sign, introduced plus and minus to Britain in 1557 in The Whetstone ofwel Witte:[14] "There be other twee signes in often use ofwel which the first is made thus + and betokeneth more: the other is thus made − and betokeneth lesse." 知乎，让每一次点击都充满意义 https://daugherty-zamora.federatedjournals.com/5-tips-over-wrapfolie-natuirsteen-motief-u-kunt-vandaag-gebruiken