verb · to have a string snap or break, such as on a guitar, kite, or fishing line

风筝断线了，飞得无影无踪。

verb · to lose a telecommunications or internet connection; to be cut off

网络连接不稳定，经常断线。

verb · to be interrupted or broken, especially regarding traditions, lineage, or processes

这项古老的技艺绝对不能断线。