While this seems doable at first, there’s a hidden difficulty when it comes to avoiding obtuse and right angles.

虽然乍一看这似乎可行，但在避免钝角和直角方面存在一个隐藏的困难。

The railway track wound in and out among the passes, now approaching the mountain–sides, now suspended over precipices, avoiding abrupt angles by bold curves, plunging into narrow defiles, which seemed to have no outlet.

这里的铁路线是顺着西埃拉山脉崎岖的山势铺设的。它忽而贴在山腰，忽而在悬崖上前进，有时为了避免急转弯，它的曲度大得惊人，有时伸入两山对峙的峡谷里，使人颇有" 山穷无路" 之感。