场景分类上生物篇第三篇bird,
3 f: Z; h% q! j: q! ]so you can never be sure about any conclusion you reach about crows from observing them applies to the whole species or just those crows you being watching.0 Y' \3 C$ W4 Q5 Y9 L; ?$ a
about--whether, being---'ve been.该这样更换吧