It has been announced that students _______ remain in their seats until all the papers have been collected.

---Did they have a good time at the party?---Judging by their smiles, they _________ have enjoyed themselves.

—Where did you meet him?—I met him on a number eleven bus, if you       know.

That man in the corner of the restaurant ______ be Mr. Lee, for he went to Australia yesterday.

 ---Let's go to the train station by bus.---We______take a bus. It is quite near from here.