Why is the present mass extinction different from the five previous ones?

(单选题)______ it is today! (单选题)The passage is less concerned with showing ______. (单选题)According to the passage, the radar boat is used for ______ (单选题)A successful channel swimmer is said to be the swimmer who _ (单选题)The main aim in training for channel swimming is ______. (单选题)In the passage, the answers can be found to all the followin (单选题)The last paragraph mainly explains ______ (单选题)The underlined word “archaic” in Paragraph 5 probably means (单选题)Marx and his colleague Ewan Fordyce discovered that ______. (单选题)Which of the following statements is TRUE?