Let all my songs gather together their diverse strains into a single current and flow to a sea of silence in one salutation to thee.
让我所有的诗歌，聚集起不同的调子，在我向你合十膜拜之中，成为一股洪流，倾注入静寂的大海。
Crash Course Physics 速成课物理
And since you no longer have a single current throughout your whole circuit, charge is not limited to one path.
而且由于整个电路中不再有单一电流，因此充电不限于一条路径。
英语百科
Neutral direct-current telegraph system
In telecommunication, a neutral direct-current telegraph system (single-current system, single-current transmission system, single-Morse system) is a telegraph system in which (a) current flows during marking intervals and no current flows during spacing intervals for the transmission of signals over a line, and (b) the direction of current flow is immaterial.