断路器跳闸是因为电路中存在故障。

The breaker tripped because there was a fault in the ___circuit.

工程师正在为这个设备设计一块新的印刷电路板。

The engineer is designing a new printed ___circuit board for the device.

如果一个元件损坏，就可能会破坏完整的电路，导致设备停止工作。

If a component fails, it can break the complete ___circuit and stop the device from working.