many/ place/ the world/,/ people/ used/ dye/ cloth/ nature/ material/.

A: In many places in the world, people used to dye cloth with natural materials.

B: In many places in the world, people used to dye cloth with nature materials.

C: In many places in the world, people used to dyeing cloth by natural materials.

D: In many places in the world, people used dyeing cloth by natural materials.

=> used to + V + ....

Dịch : Nhiều nơi trên thế giới, người ta đã từng nhuộm vải bằng nguyên liệu thiên nhiên.

many/ place/ the world/,/ people/ used/ dye/ cloth/ nature/ material/.

A: In many places in the world, people used to dye cloth with natural materials.

B: In many places in the world, people used to dye cloth with nature materials.

C: In many places in the world, people used to dyeing cloth by natural materials.

D: In many places in the world, people used dyeing cloth by natural materials.

- Do materials là noun nên trước nó là adjective 

-> B loại, chọn A

Cấu trúc :

used to + V nguyên thể : chỉ một thói quen, một hành động thường xuyên xảy ra trong quá khứ và bây giờ không còn xảy ra nữa