Under the hoarfrost the slightest twig of birches is white 在霜下桦树的最轻微的枝是白色的。
2.
Invertebrate biologist snorre hagen and his team at the university of troms ? in norway monitored the leaves and flowers of a dozen mountain birch trees for two years 因此，挪威特浪索大学的无脊椎动物学家哈根及他的团队，连续两年监测了12种山桦树的叶及花。
