输入信号从回路的起点开始，输出信号到回路的终端元件。

我试下,见笑了(不太理解你那句话的中文准确意思):
1.Signal starts from the loop input,output from the loop terminal.
2.Signal enter into the loop input side, and output from the loop terminal side.
3.Input signal starts from the loop entry, output from the loop end.
4.Signal starts from loop input,ends at the loop terminal.
5.Signal enter into the circuit input and out from the circuit terminal parts.
6.Input signal starts from the beginning of loop, output signal goes to loop end components.