特殊用法actual infinity1.实无穷minus infinity1.负无穷大, 负无限大negative infinity1.负无穷大, 负无限大plus infinity1.正无穷大, 正无限大positive infinity1.正无穷大, 正无限大polar infinity1.极性无穷大potential infinity1.潜无穷single infinity1.单重无限