He made another wonderful discovery, of great importance to science.
| A．which I think is |
| B．which I think it is |
| C．which I think it |
| D．I think which is |
_____ from endless homework on weekends, the students now can have their own activities, such as taking a ride together to watch the sunrise.
| A．Freed | B．Freeing | C．To free | D．Having freed |
You can’t imagine what difficulty we had ____ home in the snowstorm.
| A．walked | B．walk | C．to walk | D．walking |
When asked why he went there, he said he was sent there ____ for a space flight.
| A．training | B．being trained | C．to have trained | D．to be trained |
______ their hats into the air, the fans of the winning team let out loud shouts of victory.
| A．To throw | B．Thrown | C．Throwing | D．Being thrown |
They desired that they _____ the right to vote.
| A．had | B．have | C．are | D．were |