TOEFL Listening: ETS-TOEFL听力机经 - 11M4X53933NM90E9P$

Why does the professor mention a bear? A. To indicate a species the researchers expected to identify. B. To explain the variety of habitats where nests were collected. C. To illustrate how animal hairs might end up in birds' nests. D. To demonstrate why it is easier to collect nests than set traps.