Nanjing isn’t so large __________ Shanghai, however, it’s the second __________ city in East China.

I want to open the door, but it _____ open.

 ---Whose book is this?---It________ be Ning’s because it has her name on it.

You ________ in person; a telephone would have been enough.

 —Look! A book is on the floor. Whose is it?—It ______be Rick's. It has his name on it.