Sometimes they are forced to skirt the concrete machine gun emplacements of Iranian border guards, at others they have to wade across freezing mountain streams or negotiate sheer precipices.
有时，他们被迫绕过伊朗边防军的混凝土机枪阵地，有时，他们不得不趟过寒冷的山涧溪流或绕过峻峭的悬崖。
2
It is proved by a concrete example of gun barrel strength design with consistent reliability that a consistent reliability will offer a consistent safety abundance.