The little bamboo tree had been growing underground for the past four years, in the fifth year and beyond, it developed a root system strong enough for its ground growth.
过去的四年里，这株小竹子一直在地下生长，第五年开始，它形成了足够强大的根系，可以在地面生长。
2
Smaller programs will use either the systemtree or the user tree, but not both.
小型程序会使用系统树或者用户树，但是不会同时使用这两者。
3
In this step, you will traverse the source file systemtree.