[填空题]
The displacement, s , in met ew9ei (9o1qwp-pghg/ res, of a particle t e 21qdn*w;lu/rs 588ebu2x;ci t xroe seconds after it passes through the origin is given by the ex;e5cxiqor 1l w ;ndu / u*828st2erxebpression $s=\ln \left(3+t-2 e^{-t}\right)$,$ t \geq 0$ .
1. Find an expression for the velocity, v , of the particle at time t .
2. Find an expression for the acceleration, a , of the particle at time t .
3. Find the acceleration of the particle at time t=0 .