多年冻土天然上限的英文：
natural permafrost table

This is the vegetational climate of arctic permafrost regions
这是北极永冻地区的植物气候。

Perhaps this is caused by the sudden melting of subsurface permafrost
可能是地下永久冻土突然融化所造成。

Canadian researchers expressed serious concerns about the erosion of permafrost in the Arctic
加拿大研究人员对北极地区永冻层的侵蚀表示严重关切。

This table tilts.
这张桌子倾斜着。

The table was badly charred by a flatiron.
这张桌子被熨斗烧焦。

They have already engaged that table.
他们已经预订了那张桌子。