If you replace them with circular or smooth rocks, they would slide over each other and compromise the strength of the track ballast.

如果你用圆形或光滑的石头代替它们，它们就会相互滑动，损害轨道压载的强度。

The table was a nice, smooth rock.

桌子是一块漂亮、光滑的石头。

The man who followed slipped upon a smooth rock and nearly fell. He recovered his footing with great effort, at the same time uttering a sharp cry of pain.

后面那个人在一块光滑的岩石上滑了一下，差一点没摔倒。但是，他猛力一挣，站稳了，同时痛苦地尖叫了一声。

He seems to be especially fond of the larvae; of mosquitos, found in abundance attached to the bottom of smooth rock channels where the current is shallow.

他似乎特别喜欢幼虫。大量的蚊子附着在水流较浅的光滑岩石通道底部。

The general effect of these smooth rocks is indescribable: black, polished, without moss or other blemish, carved into strange shapes, sitting firmly on a carpet of sand that sparkled beneath our streams of electric light.

我不可能描写这一群平滑、黝黑、光泽、没有薛苔、没有斑点的岩石，它削成离奇古怪的形状，并且牢固地矗立在细沙形成的地毯上，沙受曳光的照耀，闪闪发亮。

Now, as the eider duck does not select steep cliffs for her nest, but rather the smooth terraced rocks which slope to the sea, the Icelandic hunter might exercise his calling without any inconvenient exertion.

现在，由于绒鸭不再选择陡峭的悬崖作为巢穴，而是选择通向大海的光滑梯田岩石，冰岛猎人可以毫不费力地履行自己的使命。