The acceleration due to gravity is insignificant compared with acceleration caused by the electric field,so the gravitation field can be ignored.Hence a particle of mass M charge q is thrown in a region where uniform gravitational field and electric field are present ,before entering electric field the charge follows a straight line path (since no net force due to any of the field).As soon as it enters the the field ,the charge begin to follow a parabolic path(since,constant forces always in the same direction).As soon as it leaves the field,the charge follows a straight line path.The path of particle may be straight line or may be parabola