[填空题]
The displacement, s , in meyh92re p x v9 /sgn1.r3;manrctres, of a particle t secondsl5,v2j 2 qfaun after it passes through t5u2ja fqv2, lnhe origin is given by the expression $s=\ln \left(3+t-2 e^{-t}\right)$,$ 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 .