There's no way of knowing why one man makes an important discovery________another man，also intelligent，fails.
| A．since | B．if | C．as | D．while |
They did the experiment in the lab _______ was named after Professor White.
| A．where | B．which | C．the one | D．what |
We must do something to ________ the factories sending out poisonous gases so as to keep the city clean and beautiful.
| A．keep | B．protect | C．permit | D．prevent |
They will move to a new apartment next month. It is _________ the one where they are living now.
| A．twice the size of | B．twice as bigger as | C．twice the size as | D．twice as bigger than |
As we know, the 2010 Word Cup _______ in South Africa on June 11, 2010.
| A．takes place | B．took place | C．is taken place | D．was taken place |
---- Liu Qian has just come back from Canada and she looks very excited.
---- She ________ her trip very much.
| A．should have enjoyed | B．might enjoy | C．must enjoy | D．must have enjoyed |