Organisms play ________ important role in keeping the nature balanced.

I love learning about _________ life under the sea.

Oceans altogether cover 75 __________ of our Earth.

They can send submarines to take photographs of animal life and bring back to the __________ for further study.

I _________ smoking should be banned, especially in restaurants.

A large number of jellyfish are _________ stake due to overhunting.

A big ocean in the world is divided ___________ five different parts: the Pacific, Atlantic, Indian, Antarctic and Arctic Oceans.