  ![[]{data-label="f00u"}](F0u.eps){width="0.0in"}  ![[]{data-label="f00u"}](F0u.eps){width="0.0in"}  [Case 0]{}. Let $A_0=0$, $A_0=0$, $B=0$, $D=0$, then we have $$\begin{aligned} \left\{\begin{array}{l} p_0(t)=