It was slender and straight, and its smooth bark was a beautiful light-green color.

它又细又直，光滑的树皮泛着美丽的淡绿色。

Then with a knife he inscribed on the smooth bark of a beech tree the letters M.T., and underneath a large X.

然后，他用一把刀在一棵山毛榉树光滑的树皮上刻下了字母 M.T.，并在下方刻下了一个大 X。