The XML Infoset is very similar to a tree structure and it is easy to construct a graph that is not a tree (just connect the nodes in such a way so that there is no obvious root node).

XML Infoset与树结构非常相似，而且易于构造不是树的图(只需以不产生明显的根节点的方式连接节点)。

youdao

One person may go from Phase 4 to Phase 5 and then back to Phase 2 again; that is why there is no easy way to determine how long a change will take to implement.

有些人可能已从第四阶段进入第五阶段，但一下子又从新跳入第二阶段；这就是为什么计算一场变革需要花多长时间是很难的。

youdao

The problem is that medullary cancer is so rare and develops so slowly over decades, that there is be no easy way to rule out the possibility that the drugs might boost cancer risk decades after people start taking them.

FORBES: Drug Safety

But the fortunes of the Cup holders have been transformed since that defeat, and Vickery says there is no easy way to win the ultimate prize.

BBC: Boks defeat still hurts - Vickery