. -- Do you think Allan came by taxi?-- No. If he had, I don't believe he ______ his bike here.
You can only be sure of _____ you have at present;you cannot be sure of something _____ you might get in the future.
The company was named Gates Hall ______ a man named James Gates.
— Has Mary finished writing her article? — No, and it _____ before class was over.
—Your mother becomes more and more forgetful. —Yes. She searched for her cellphone for a whole day last Sunday but it ______ in her coat pocket the next day.
—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.