1. Many dinosaurs have become extinct.
许多恐龙已经灭绝。
2. This species may become extinct in the future.
这个物种可能在未来灭绝。
3. Extinction is a result of natural selection.
灭绝是自然选择的结果。
4. Scientists are working to prevent species from becoming extinct.
科学家正在努力防止物种灭绝。
5. Some animals have become extinct due to habitat destruction.
某些动物因为栖息地破坏而灭绝。