She couldn’t find her son she had dropped him off.
| A．when | B．until |
| C．although | D．where |
As early as 1647 Ohio made a decision that free, tax supported schools must beestablished in every town _____ 50 households or more.
| A．having | B．to have | C．to have had | D．having had |
Although punctual himself, the professor was quite used _____ late for his lecture.
| A．to have students | B．for students' being |
| C．for students to be | D．to students' being |
The pressure _____ causes Americans to be energetic, but it also puts them undera constant emotional strain (过度紧张).
| A．to compete | B．competing |
| C．to be competed | D．having competed |
_____ it or not, his discovery has created a stir in scientific circles.
| A．Believe | B．To believe | C．Believing | D．Believed |
After the Arab states won independence, great emphasis was laid on expanding education, with girls as well as boys _____ to go to school.
| A．to be encouraged | B．been encouraged |
| C．encouraged | D．be encouraged |