—Who______ it be that is knocking at the door?
—It ______ be Father, but I’m not sure.
| A．can; must | B．can; may | C．must; can | D．may; must |
Mr. Smith is _______ success as a businessman; he takes _______possession of several big companies.
| A．a; the | B．a; / | C．/; a | D．/; the |
Ten years ago, the population of our village was ______ that of theirs.
| A．as twice large as | B．twice as large as |
| C．twice as much as | D．as twice much as |
She has been working hard day and night, which of course, _______ her pale face.
| A．accounts for | B．stands for | C．goes for | D．answers for |
--- Are you satisfied with what he did?
--- No. It couldn’t have been ______.
| A．worse | B．better | C．so bad | D．the worst |
--- He worked out such different questions at a very young age.
--- Oh, he ______ a very smart student then.
| A．could have been | B．should have been |
| C．might have been | D．must have been |