The properties of the operators of modal logic system S5 is investigated, then a theorem is proved about its primitive operator set, and some corollaries are given.

探讨了模态逻辑系统s5的运算子性质，进而证明关于它的本原运算子集的一个定理，并给出一些推论。

youdao

The care-home operator is set to shut down, after landlords owning all 752 of its care homes said they wanted to leave the group.

BBC: Urgent question: Southern Cross

The operator is set to eventually deploy a Wi-Fi network across the entire Square Mile, London's main financial district, and is launching a number of city center "hotzones" around Britain.

FORBES: Citron's Vonage Expands Wi-Fi Phone Service In U.K.

When Celtel, a mobile-phone operator, set up in Zambia eight years ago, it concentrated on the densely populated corridor between Victoria Falls (on the border with Zimbabwe), Lusaka and the industrial copper belt.

ECONOMIST: Business in Africa