It is estimated that an wild adult male koala enjoys an average life-span of______.
举一反三
- 【单选题】生成如下数据框的语句是? weight height gender age 1 80 180 male teen 2 75 170 male teen 3 60 165 female adult 4 52 150 female adult A. X ,gender=c("male", "male", "female", "female"),age=c("teen","teen","adult","adult")) B. X ,gender=c("male", "male", "female", "female"),age=c("teen","teen","adult","adult")) C. X ,gender=c(male, male, female, female),age=c(teen,teen,adult,adult)) D. X ,gender=c("male", "male", "female", "female"),age=c("teen","teen","adult","adult"))
- What can we infer from the text A: It is easy to prolong the average life span in developed country, because of the advanced health science. B: It is difficult to prolong the average life span greatly, because science cannot prevent the aging process now. C: If the diseases that cause most of the death can be cured, the average life span will increase greatly. D: More and more people will live past 100 if the diseases that cause most of the death can be cured.
- The average life-span of Americans is 80 years. （） A: Right B: Wrong C: Not mentioned
- 6. Throughout most of history, the average human life span was probably only around thirty to forty years. A: B:
- the average life