If ____unsolved, the problem of food safety may lead to more serious results.
| A．left | B．making | C．remained | D．taking |
29. That's all for the party. Let's _____.
| A．fall asleep | B．go to sleep | C．go to bed | D．be asleep |
28. They ____ friends since they met in Shanghai ten years ago.
| A．have become | B．have turned | C．have been | D．have grown |
27. When he heard the news, his heart ______ very fast.
| A．stroke | B．beat | C．knocked | D．Jumped |
26. The old woman could not _____ the terrible noise, and she had to close the door and windows.
| A．bear | B．accept | C．receive | D．Hold |
25. --- We could have walked to the station. It was so near.
--- Yes. A taxi ____ at all necessary.
| A．wasn’t | B．hadn’t been | C．couldn’t be | D．wouldn’t be |