Experiments of this kind __________ in both the U. S. and Europe well before the Second World War.
| A．have conducted |
| B．have been conducted |
| C．had conducted |
| D．had been conducted |
The first African-American president of the United States received a（n） _____ welcome in the African countries, where he was received as a returning son．
| A．romantic | B．bureaucratic | C．enthusiastic | D．optimistic |
Several years after they got married he ____ chatting on the Internet until very late, which eventually resulted in their divorce.
| A．took on | B．came to | C．took to | D．came about |
| A．hope; are bound | B．hopes; is bound |
| C．hope; are due | D．hopes; is due |
Fireworks exploded during _____ opening ceremony of _____ 2011 Asian Cup football tournament at Khalifa Stadium．
| A．the; a | B．the: the | C．a; a | D．a; the |
— Frank, I’ve learned your plan. Could I make some suggestions?
— ________.
| A．Just for fun | B．Go ahead | C．With pleasure | D．Take it easy |