请帮忙翻译成英文：他们会在15天以后考虑材料的事

they will consider the matter of material after 15 days.

they will consider the matter of materials in 15 days.

注意哦，after一般用过去时
in 15 days 比较正规

材料是可数的，因为不只一种材料啊。

They will consider the matter of material in 15 days

They later will consider the material in 15 days the matter

They will think about the business of materials 15 days later

楼上的对