阿摩線上測驗
8. Every once _____ a while, David treats his customers to
lunch.
(A) at
(B) in
(C) on
(D) to
答案：登入後查看
統計： A(38), B(290), C(63), D(11), E(0) #2228402
統計： A(38), B(290), C(63), D(11), E(0) #2228402
