凡是光不能穿过的物体都是不透明的。石头墙不透明。

Anything that does not allow light pass through it is opaque. A stone wall is opaque.

youdao

那些留在这里的人也厌倦了生活在这样一个地方，在这里，如果不穿过一群正在拍照的游客，他们甚至都不能去市场。

Those who stick around are tired of living in a place where they can't even get to the market without swimming through a sea of picture-snapping tourists.

youdao

这台机器是如此精确，以至于人类的头发甚至不能从头部和旋转的磁盘之间穿过，但它的运转速度却是惊人的。

This machinery is so precise that a human hair couldn't even pass between the heads and spinning platters, yet it all works in terrific speeds.

youdao

And that's all that's big enough to pass through or small enough to pass through. And if we go up even just one row on the periodic table to potassium, what we actually see is now that it's going to be too large, and, in fact, a potassium solvated with one water molecule won't go through our channel.

就是这样刚好大到它通过,或者说刚好小到它通过,即使我们再沿着周期表往下走仅仅一行到钾离子，我们看到的就将是它的个头太大了，实际上，溶解于一个水分子的单个钾离子,不能穿过我们的通道。

麻省理工公开课 - 化学原理课程节选