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
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