Exploring _____space is exciting, yet dangerous.
There is _____need for both robots and humans for space exploration.
| A．the; a | B．a; a | C．/; a | D．/; the |
The World War II made_________ impossible for Einstein to go on with his research.
| A．him | B．it | C．this | D．that |
We had _________ great fun at the charity party yesterday. I have never had _________ more exciting experience.
| A．a, / | B．/, a | C．/, the | D．the, a |
The scientists were trying to look for all possible _______ as to where this species came from.
| A．signals | B．marks | C．clues | D．spots |
A well-written speech ______ a lot, such as a good choice of words, a clear
structure, a distinct theme, etc.
| A．calls on | B．calls for | C．calls up | D．calls off |
Lisa made a(n) _____ to help her husband with the problem, but failed in the end.
| A．promise | B．response | C．decision | D．attempt |