_______, there would be no air around the earth.
| A．There were no gravity | B．There was not any gravity |
| C．Were there no gravity | D．was there no gravity |
We can never expect ______ bluer sky unless we stop ______ industrial waste going into _____ atmosphere.
| A．a; the; the | B．the; the; the | C．a; /; the | D．the; /; / |
________that he made an obvious mistake，Jeff went on with his speech.
| A．Not realized | B．Not realizing |
| C．Not to realize | D．Not to have realized |
There is no doubt ________ those who work hard will succeed sooner or later.
| A．if | B．whether | C．why | D．that |
There are many websites，________you can find almost all the necessary information.
| A．where | B．from where | C．when | D．from when |
If we _______ adequate preparations, the conference wouldn’t have been so successful.
| A．haven’t made | B．wouldn’t make | C．didn’t make | D．hadn’t made |