The mechanical properties of improved double-base propellants enabled one to envisage grain geometrics with large combustion areas and consequently high thrusts . 经过改进的双基推进剂的机械性能使我们能够指望获得大燃烧面的药柱几何形状，从而得到大推力。
2.
Whatever this reason ? to provide a common experience for students , to control the arrival of students , even non - canonical magical geometrics ? it is likely that some equivalent experience existed prior to the train 这当然可能很壮观，但大概没有一列穿越了大半个英国，却又很好地遮挡了麻瓜耳目的深红色列车那么显眼。
