一、根据首字母或汉语提示完成下列句中所缺的单词。
1. An ______ （成年的）elephant is about 350 cm tall.
2. Once upon a time, a big stone gave ______ （出生）to a baby.
3. The river is very ______ （深的）. You’d better not swim in it. It’s too dangerous.
4. The two astronauts will do ______ （研究）in space.
5. The ______ （政府）allows every couple to have two children.
