They have spent a lot of on building ____________(材料）,such as bricks and sand.
问题描述：
They have spent a lot of on building ____________(材料）,such as bricks and sand.
答
materials或material.注意material做材料讲可数不可数都可.下面是material不同意思时的可数情况：
1.材料,原料（可数或不可数）
2.衣料,织物（可数或不可数）
3.素材,资料,要素（不可数）