阿摩線上測驗
39. What is the main reason that liquid sewage needs to go through sand?
(A) To eliminate bacteria.
(B) To drain water.
(C) To dissolve solid particles.
(D) To remove oil.
答案：登入後查看
統計： A(183), B(21), C(29), D(7), E(0) #2379978
統計： A(183), B(21), C(29), D(7), E(0) #2379978
