code class$=$"asciimath"$>$The breakover voltage of the two silicon diodes D$\_($A$)$ and D$\_($B$)$ is $0\mathrm{.}7$V$.$ Given the circuit below, when V$\_($A$)=4$V and V$\_($B$)=2$V$,$ the output voltage V$\_($O$)$ is aV$\_(0)=3$V $(4\%)$