6.
What do three hearts,eight arms,and one huge brain add up to?An octopus-a sea animal that can do amazing things.
Octopuses are very smart.They can learn new things just like humans.They've even learned a few skills to get themselves out of dangerous situations.Octopuses don't have teeth or sharp (鋒利的) claws to protect themselves.Instead,they use more clever ways to fool their enemies.Octopuses like to hide themselves in the sand on the bottom of the ocean floor.It can change the color of its skin to match the sand.And this color change happens in less than a minute.
Some octopuses like to stay near rocks in shallow water.They can make themselves fit into small spaces between the rocks to get out of reach of their enemies.Another way an octopus can hide is by shooting ink.The ink forms a cloud that hides the octopus.By the time the ink clears,the octopus has swum away or hidden.
If an octopus is in danger,it can make itself look like a sea snake.It will hide itself in the sand,leaving two arms outside.It will change the color of those arms to match a sea snake.But what if there's no time to hide?It can break off one of its arms.The arm will then change colors and keep moving around in the water to take the enemy's attention away while the octopus swims away to safety.Don't worry though.The arm will grow back.
A kind of octopus is called the blue-ringed octopus.It is tiny.But the enemies know to stay away because it is very poisonous and can kill animals much larger than itself,including humans.
So the next time you see an octopus in the aquarium,remember that inside that oversized head is a very large brain,making it a clever addition to the sea.
53.The octopus breaks off one of its arms toC.
A.fit into small spaces
B.swim much faster
C.get time to run away
D.shoot more ink
54.Which of the following is true according to the passage?D
A.The octopus has sharp teeth to catch food.
B.The octopus uses its arms to kill the enemy.
C.The octopus changes color to fool the sea snake.
D.The octopus can make itself look like another animal.
55.The passage is mainly aboutB.
A.how careful the octopus is to hide itself
B.how clever the octopus is to protect itself
C.how happy the octopus is to live in water
D.how brave the octopus is to face dangers.