16. Children are not allowed to use the swimming pool __________ they are with an adult.
(A) in case
(B) provided
(C) unless
(D) as long as

答案：登入後查看
統計： A(23), B(21), C(226), D(17), E(0) #361750

詳解 (共 1 筆)

#1067431

 (C) unless 除非

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