1. The walls of the fortress were made of imperviable stone, making it difficult for enemies to break through.
（这座要塞的墙壁是由无法穿透的石头建造而成的，使敌人难以突破。）
2. The raincoat is made of imperviable material, so you won't get wet even in heavy rain.
（这件雨衣是由不透水的材料制成的，所以即使在大雨中你也不会被淋湿。）