A charged particle is released from rest in a region of steady and uniform electric and magnetic fields which are parallel to each other. The particle will move in a

$\vec{E}\parallel \vec{B}$
$F_E=q\vec{E}$
$$F_B= q(\vec{v} \times \vec{B}$$
given $\vec{v}$  is parallel to  $\vec{B}$
$\Rightarrow F_B=0$ since  $\sin \theta =\sin 0^{\circ }=0$
$\therefore$ the charged particle will accelerate and move in a straight line.