________ these experiments were successfully completed would we think of going into humans.
| A．If only | B．Only if | C．So that | D．Even if |
Obama has been elected___first black president of the United States,and the international society expects to have___new USA under his leadership
| A．/;the |
| B．a;the |
| C．the;a |
| D．the;the |
When you drive the car,you can never be___careful to do it
| A．so |
| B．very |
| C．too |
| D．that |
I am delighted___as chairman of the students’ union last winter
| A．to appoint |
| B．to be appointed |
| C．to have appointed |
| D．to have been appointed |
He’s been___to the State Supreme Court in Clifornia
| A．determined |
| B．appointed |
| C．admitted |
| D．assumed |
The custom has been___since the 18th century
| A．handed over |
| B．handed down |
| C．handed out |
| D．handed in |