20．Though ________ money, his parents managed to send him to university．
| A．lack | B．lacking of |
| C．lacked | D．lacking |
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 |
Life is like time. Once _____, it never returns.
| A．to lose | B．losing | C．lost | D．being lost |
The company gave away 300 dictionaries to the students at the beginning of the term, and _____500 the next term.
| A．more | B．another | C．other | D．further |
While many believe Benjamin Franklin to have discovered electricity, recent findings seem to show _____.
| A．anyway | B．otherwise | C．somehow | D．so |
— Can I smoke in this hall?
— No, you can’t. If you _____, please go to the smoking room.
| A．should | B．might | C．can | D．must |