—The window is dirty.
—I know. It ______ for weeks.
| A．hasn’t cleaned | B．didn’t clean |
| C．wasn’t cleaned | D．hasn’t been cleaned |
This book is said to be a very special one, because it _______ many events not found in other history books.
| A．covers | B．writes | C．prints | D．reads |
For quite a few students, their teacher’s advice is more important than ___ of their parents.
| A．one | B．that | C．it | D．any |
Some scientists believe that it won’t be long _______ robots are widely used in all walks of life．
| A．since | B．after | C．before | D．until |
The number of deaths from heart disease will be reduced greatly if people_______ to eat more fruit and vegetables.
| A．persuade | B．will persuade |
| C．be persuaded | D．are persuaded |
The famous reporter, who is said to have gone back to America last year, _____in China for almost twenty years．
| A．lived | B．was living |
| C．has lived | D．have been living |