The passage is chiefly about ______. A: an effort to protect an endangered marine species B: the civilian use of a military detection system C: the exposure of a U. S. Navy top-secret weapon D: a new way to look into the behavior of blue whales

The passage is chiefly about______ . A: an effort to protect an endangered marine species B: the civilian use of a military detection system C: the exposure of a U. S. Navy top-secret weapon D: a new way to look into die behavior of blue whales

What does it mean for polar bears to be made onto the endangered species list（） A: They can be kept away from dangers. B: They can become the center of the attention. C: They can get protection from laws. D: They will not die out in the future.

It can be inferred from the passage that the polar bear population of Hudson Bay ________. A: is one of several polar bear populations B: is unfriendly toward humans C: consumes food voraciously (贪婪地) during the whole year D: is an endangered species

The amino acid sequence of cytochrome c is used to reveal the organisms that are most closely related. Which of the following organisms are most closely related? A: Species R and S B: Species S and T C: Species T and W D: Species S and W