TOEFL Reading: ETS-TOEFL阅读机经 - 6M3302X6FQFTD4EIL$

In paragraph 5, coral reefs in the Indian Ocean are presented as an example of which of the following A. Ecosystems that totally collapsed B. Ecosystems that transitioned to a new, healthy state C. Ecosystems that bounced back to the way they were D. Ecosystems that were affected by a nearby dead zone