TOEFL Reading: ETS-TOEFL阅读机经 - 7O_078W12YV1L544L$

Paragraph 4 suggests which of the following about the Alvarezes' theory A. Their theory was accepted until 1980, when more focused investigations showed it to be incorrect. B. It rules out the possibility that the iridium spike was the result of volcanic activity. C. Before it can be accepted, more evidence must be gathered from locations outside Europe and New Zealand. D. Experts believe the research done by the Alvarezes was too broad.