1011101:but when is the line crossed between average use and

1011101:but when is the line crossed between average use and addiction?
想知道的语言点：
1—when is the line crossed:这里的line crossed 怎么翻译?
2—between average use and addiction:怎么翻译?
1_but when is the line crossed between average use and addiction?
when is the line crossed ：这是个疑问句 因为is跟在when后 line：界限
翻译：当界限被超越
crossed：adj 十字的,划掉的,交叉的
cross：vt 1.反对,阻挠; 使受挫折2.在…上打叉，划掉，注销，勾销(常与 off，out 连用)3.公开反对；反驳；否定；阻挠4.横过
average use 平均使用 addiction成瘾
翻译：但是当界限被超越在平均使用和成瘾之间。
翻译：但是在平均使用和成瘾之间，当界限被超越。