用括号中所给单词的适当形式填空。
1. The ________ dinosaur has not disappeared.(feather)
2. He wants________ a scientist in the future.(be)
3. The scientists try to explain their ________.(disappear)
4. The ground ________ with snow now.(cover)
5. Human ________ mean men, women and children.(be)
1.feathered 2.to be 3.disappearance 4.is covered 5.beings