—Look! A book is on the floor. Whose is it?—It ______ be Rick’s. It has his name on it.

—May I do the rest of the work tomorrow?—Yes, of course. You        finish it today.

 —Must I wait for you here?—No, you ______. 

I can’t find my socks. Where ________ I have dropped them?

Miss Li regards all her students _______ her children.