The climbers rested on a sheltered ledge jutting out from the cliff.

登山者在悬崖的岩棚休息。

The phone was perched precariously on the window ledge.

电话放在窗台，摇摇欲坠。

If the emitter ledge is too thick, current will flow through the undepleted ledge, which increases the emitter-size effect.

不适当的射极部厚度，将会在射极部侧壁造成严重的表面复合。