题干
—European scientists announced that the speed of light isn’t the speed limit.
—Perhaps it is the biggest challenge to Einstein’s Theory of Relativity. No one ________ any crack in his theory for more than a century.
—Perhaps it is the biggest challenge to Einstein’s Theory of Relativity. No one ________ any crack in his theory for more than a century.
| A．has found | B．found | C．had found | D．would find |
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