Believe it or not, my sister and I are twins.— Oh, you must have had the case _________ you were taken for your sister.

If you have any trouble, be sure to call me.—_________________________.

－When did you today－At 8:00.

They listened to my lecture, but how much did they ________, I wonder?[ ]

Not until he called the secretary threetimes _________ that the manager went to an important meeting.