Green sea turtles(海龟) are the world’ s largest species of hard-shelled sea turtle. While most individuals weigh about 136 to 181 kilograms, some can be (56)\_\_\_\__ heavy as 204 kilograms. These tu
Passage 2Questions 6 to 10 are based on the following passage: Half of the world’s coral reefs(珊瑚礁) have died in the last 30 years. Now scientists are racing to ensure that the rest survive. Even if