| Song | 真题模拟12 |
| Artist | 英语听力 |
| Album | 英语专四听力周计划 |
| About 40% of the different kinds of sharks lay eggs. The others give birth to live young. Some sharks carry their young inside their bodies like humans do. Scientists are beginning to understand the importance of sharks to humans. Medical researchers want to learn more about the shark's body defense system against diseases. They know that sharks recover quickly from injuries. Sharks appear never to suffer infections, cancer or heart disease. |