当且仅当这些行为发生时，在上级和下级之间才存在一种权威关系。

When, and only when, these behaviors occur, does an authority relationship exist between the superior and subordinate.

youdao

当且仅当有可重复的科学证据证明蝾螈之眼有效时，蝾螈之眼才会进入小黑袋中。

Eye of newt goes into the little black bag, if and only if there is reproducible scientific evidence that it works.

youdao

这是正确的，因为上面对 a 和 b 的奇偶性的推导是一个当且仅当命题。

This is true as the above derivation for a and b of opposite parity is an if and only if statement.

youdao

A very important result is that if two vectors are equal, if A = B, the only way it can happen is if separately Ax is equal to Bx and Ay is equal to By.

这里有一个相当重要的结论,如果两个矢量相等,例如 A = B,那么当且仅当,Ax = Bx 和 Ay = By 分别成立

耶鲁公开课 - 基础物理课程节选

I'll say it again, Player i's strategy "s'i" is weakly dominated by her strategy "si" if she always does at least as well by choosing "si" than choosing "s'i" regardless of what everyone else does, and sometimes she does strictly better.

重申一下,参与者i的策略s'i,弱劣于策略si,当且仅当无论对手怎么做,她选择si的收益至少与选s'i的相等,有些情况下甚至是严格占优的

耶鲁公开课 - 博弈论课程节选