1.美洲羚羊，或称叉角羚，是该大陆典型的草原动物。

2. Of the millions who saw Haley’s comet in 1986, how many people will live long enough to see it return in the twenty-first century.

2. 1986年看见哈雷慧星的千百万人当中，有多少人能够长寿到足以目睹它在二十一世纪的回归呢？

3. Anthropologists have discovered that fear, happiness, sadness, and surprise are universally reflected in facial expressions.

3.人类学家们已经发现，恐惧，快乐，悲伤和惊奇都会行之于色，这在全人类是共通的。