根据句意及首字母提示，补全单词。
1. Do you know the whales are the e_ __ animals in the sea?
2. The little monkey is very p______. Look! He is trying to catch the food from his mother.
3. More and more rivers are p__ _ by the chemical factories. Our drinking water is less and less.
4. All of teenagers will get best e ____ in our village with the help of our teachers.
5. Can you w_ how heavy the elephant is without any help?
