—Only one of these books is worth _______.—_______ is no wonder that you look so upset.
_____ on folk tales, Mo Yan's novels become a mixture of fantasy and reality.
No matter how busy he is, he makes _____a rule to surf the Internet for information.
— Tom was late for work this afternoon.— _____?As far as I know, he is fairly punctual.
— I rang you at about nine, but there was no reply.— Oh, that was probably _____I was seeing the doctor.
— There'ssomeone knocking on the door. Who _____it be?— It must be Mary. She promised to be here at 8:00.