_________as one of the most important inventions of the time, the computer helps people living in different countries to do a lot of things.
| A．Knowing | B．Known |
| C．To know | D．Know |
Nelson Mandela__________ peacefully at his Johannesburg home on Thursday，President Jacob Zuma said.
| A．dies | B．died | C．has died | D．had died |
“Rubber Duck”,________ by Dutch artist Florentijn Hofman，has visited many cities since 2007．
| A．being created | B．creating | C．created | D．having created |
Of the two-child policy，_________ some see the bright side，others worry about a baby
boom in China．
| A．while | B．when | C．since | D．once |
“OK．Bingo!We win．_________, mom!” shouted Daniel，raising his hand．
| A．Give me five | B．You don’t say | C．Good heavens | D．Don’t mention it |
Last night, before the exam, I went over the lessons I couldn’t keep my eyes open to stay awake any longer.
| A．before | B．until | C．unless | D．when |