County X and County Y have similar terrain, but the population density of County X is significantly higher than that of County Y.

X 县和 Y 县的地形相似，但 X 县的人口密度显著高于 Y 县。

youdao

X coordinates: The X coordinate is a point's horizontal distance from the origin.

X 坐标：X 坐标是某一个点距离原点的水平距离。

youdao

And the symbols are only letters. So a of X says that X is a man.

符号仅仅是字母，所以X的A说，X是一个人。

youdao

"One of the really frustrating things for patients with fibromyalgia is that there's nothing to measure in labs or in X-rays.

VOA: special.2011.08.02

The highest probability now is going to be along the x-axis, so that means we're going to have a positive wave function every place where x is positive.

概率最高的地方是沿着ｘ轴，这意味着只要在ｘ,大于零的地方波函数都是正的。

麻省理工公开课 - 化学原理课程节选

The power of linearity is F=k1+k2 if I come across f of x, y, z equals k1 plus k2, if it is a linear equation, I don't have to go and solve it all over again.

线性的威力是,一个方程，如果它是个线性方程，那么我就不用再去解他了。

麻省理工公开课 - 固态化学导论课程节选

While some experts insist Syndrome X is a disease and that a genetic flaw is the cause, others argue Syndrome X is merely a precursor to other ailments, including heart disease and adult-onset diabetes.

FORBES: The Unknown Epidemic

Civilians get onto aircraft and their luggage is x-rayed, but the cargo hold is not x-rayed.

NPR: Transcript of Presidential Debate

In terms of build quality, it's on par with the Air, and there's an argument to be made that its matte, 400-nit, 1600 x 900 display is actually better than the reflective 1440 x 900 Apple is offering.

ENGADGET: MacBook Air review (13-inch, mid 2012)