— The floor is too dirty.
— I know. It _______ for weeks.
| A．hasn’t cleaned | B．didn’t clean |
| C．hasn’t been cleaned | D．wasn’t cleaned |
Although some boys in his situationto crime to get money for food and clothing, Louis never did.
| A．might have turned | B．might be turning |
| C．had turned | D．will turned |
There’s a fascinating driveout for tourists.
| A．to mark | B．to be marked | C．marking | D．marked |
His music is popular today as it ever was.
| A．very | B．as | C．such | D．so |
Cloning plants is straightforward cloning animals is very complicated .
| A．so that | B．although | C．while | D．as if |
The popularity of films such as Jurassic Park,a scientist clones several kinds of extinct dinosaurs, proves how the idea struck a mixture of fear and excitement into people’s hearts.
| A．which | B．what | C．in which | D．that |