Complete the words from 0 to 10 Bottlenose dolphins

live in oceans around the world where the climate is (0)
They measure between two and four metres (1) length and their powerful tails
help them swim (2) fast. Bottlenose dolphins always (3) to be smiling, which is
because of the (4) of their mouths. Because they are sociable creatures, they live
in groups of between ten and fifteen dolphins. They hunt and play together and help
each other (5) after the baby dolphins.
6)... they live underwater, dolphins have to come up to breathe air at least once
every seven minutes. They can also jump up to five metres out of the water.
Scientists are not totally (7) why they do this. It (8) , be just for fun or perhaps
they are trying to find food. Other possibilities are that they do it to (9) . with other
dolphins, or even (10) , a way of cleaning themselves.​