题目内容：

Each zebra has its own unique pattern of distinctive stripes (带), just 1.humans have their own unique pattern of fingerprints, Zebras stick together in herds (兽群). Within a herd, zebras tend 2. (stay) together in smaller family groups. Families are generally made up of a male, several females, 3.their young.

As zebras graze, they use their sharper front teeth to bite the grass, and then use their duller back teeth to crush and grind. A zebra’s teeth keep growing for 4. (it) entire life, because constant chewing 5. (wear) them down.

Zebras are6. (constant) on the move to find fresh grass and water. Sometimes they gather in huge herds of thousands as they migrate to better feeding7. (area). They often travel in8. (mix) herds with other grazers and browsers, such as wildebeest.

Zebras groom (理毛) one another, If you see two zebras standing close9. each other and it looks like they’re biting each other, don’t worry. They’re pulling loose hairs off each other as they groom. Grooming also feels good to a zebra—it’s like having an itch scratched,

While most zebras are least endangered, Grevy’s Zebra 10. (classify) as endangered.