Read the text below and choose the word that fits best for each space. The first one is done for you. Have you ever seen dolphins? Dolphins are mammals that (0) _______ in seas and oceans. Dolphins are smart animals, but they are (1) _______ curious and playful. One of the most (2) _______ facts about dolphins is how much they enjoy playing. Dolphins can (3) _______ jumping above the surface of the water and landing on their backs, bellies, or sides just for fun. Dolphins even find ways to entertain (4) _______ under the water. (5) _______ they do not have objects to play with, they make (6) _______ own toys out of air! (7) _______ fish, dolphins are mammals that breathe air. They can stay under the water (8) _______ 15 minutes with one breath. Dolphins can control when they breathe out. The air comes out through their blowholes and makes bubbles. One kind of air bubble is shaped (9) _______ a circle. It (10) _______ a bubble ring, and it happens to be the perfect sea toy. Many scientists (11) _______ filmed and photographed dolphins playing with bubble rings. Sometimes (12) _______ looks like dolphins use the bubble rings as targets. They will hit the bubbles with their long noses or spin around and slap the bubbles with their tails. Dolphins also try to bite the bubbles. (13) _______ dolphins use bubble rings to create more of a challenge. (14) _______ playful mammals will make a big bubble ring and try to swim through it. They have been seen trying to catch a bubble ring or move it around without breaking it. Sometimes they can (15) _______ two or three bubble rings together. It is (16) _______ fun game for the dolphins! (17) _______ experts think that dolphins also use bubble rings to help them hunt for food. Dolphins swim beneath the fish and send up bubbles. The bubbles cause the fish to move toward the surface of the water. (18) _______ the dolphins swim in and grab a tasty snack. It is amazing (19) _______ dolphins play with bubble rings. It does not matter if dolphins use bubble rings to help them hunt for food or use them just for fun. What matters (20) _______ dolphins have fun playing with all the bubbles they make.