阿摩線上測驗
13. Today, air pollution causes several serious problems worldwide, one of ______ is acid rain.
(A) those
(B) that
(C) them
(D) which
答案：登入後查看
統計： A(59), B(34), C(59), D(121), E(0) #2472225
統計： A(59), B(34), C(59), D(121), E(0) #2472225
