We can write out what it is for any certain atom or ion x, X so it's just x plus an electron gives us x minus.

我们可以用，X，来表示一个任意的原子或离子，因此可以写成，X，加一个电子等于负一价的。

youdao

Namely, let's say that you have a function maybe of three variables, x, y, z, df = fxdx+fydy +fzdz then you would write df equals f sub x dx plus f sub y dy plus f sub z dz.

即是说，如果你有一个,含自变量，x，y，z的函数，那么。

youdao

Namely, we will be saying the /a normal vector is x, y, z over a, plus or minus depending on whether we want it pointing in or out.

我们容易知道,法向量为，正负号取决于它是指向外面还是里面。

youdao

It can be x plus some change in x plus j times y plus a change in y.

可以写成 x 加上 x 方向的变化量,再加上 y 加上 y 方向的变化量

耶鲁公开课 - 基础物理课程节选

Initially, its location as a function of time is equal to i times x plus j times y.

初始时刻,它的位移作为时间的函数等于,i ? x + j ? y

耶鲁公开课 - 基础物理课程节选

We can write out what it is for any certain atom or ion x, X so it's just x plus an electron gives us x minus.

我们可以用，X，来表示一个任意的原子或离子，因此可以写成，X，加一个电子等于负一价的。

麻省理工公开课 - 化学原理课程节选

Below that is a row of four test tubes, marked with a circle, an X, a square and a plus sign.

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