—You may find the key to the math problem on page 107．
—Ah, it's so simple． I wonder why I _ of that．
| A．hadn't thought | B．haven't thought |
| C．didn't think | D．wasn't thinking |
27. He couldn’t ______ the fact that the money was found in his house.
| A．answer for | B．leave for | C．account for | D．care for |
26. —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 |
25.—Why is Mr. Li so happy this morning?
—Because he was honoured with a(n)______ for excellence in teaching.
| A．present | B．gift | C．award | D．Reward |
23. The day ______ she spent with us was never to be forgotten.
| A．when | B．on which | C．that | D．in which |
22. Let’s ______my scientific knowledge and your business skills and start a company.
| A．connect | B．relate | C．combine | D．Put |