Permian extinction occurred______.A.300 million y

The study of the end－Permian mass extinction is hindered by all of the following EXCEPT __

Fossil records indicate______existing in the past have become extinct.A．that many species

The passage is against the idea that______.A．human activities lead to the extinction of so

Some species of animals have become extinct because they could not ______ to the environme

______she had forgotten to take her notebook.A．That occurred to herB．She occurred thatC．

One way to preserve species _____ threat of extinction is to remove them to zoos an