Câu hỏi

The secrecy of the police operation against the gang was complete. It seems only in jail did its bosses discover their phone calls……………listened to for months.

• A were being              
• B had been
• C were
• D have-been

Luyện Bài Tập Trắc nghiệm Tiếng Anh 12 mới - Xem ngay