对任意<img class=jc-formula data-tex=A,B\in F src=https://huaweicloudobs.ahjxjy.cn/F3D14591D01F0CA1A92A56FBCAE958DF.png style=vertical-align: middle;/>,则<img class=jc-formula data-tex=P(A-B)=P(A)-P(B) src=https://huaweicloudobs.ahjxjy.cn/0B32C29C079587980B49094D3DEB9C00.png style=vertical-align: middle;/>