Fish live in saltwater and freshwater all over the world. They come in many different shapes and sizes, but most are covered in scales and have strong fins for swimming. A fish’s scales all lie in the same direction to help the fish slip through water.Like us, fish need oxygen to live. But instead of breathing air, they absorb the oxygen in water. Water enters the mouth and is swept over the gills. The oxygen passes from the water into tiny blood vessels in the gills.

Fish often swim in groups called shoals. One reason they do this is for protection. Many fish together can confuse a predator. This makes it hard for the predator to single out a fish.

Fish has a lot of benefits for human being. It is a high-protein, low-fat food that provides a range of health benefits. White-fleshed fish, in particular, is lower in fat than any other source of animal protein, and oily fish are high in omega-3 fatty acids, or the "good" fats. Since the human body can’t make significant amounts of these essential nutrients, fish are an important part of the diet. Also, fish are low in the "bad" fats commonly found in red meat, called omega-6 fatty acids.

15.    What is the main idea of the third paragraph?

A.    Fish often avoid the predator                       

B.    How fish avoid the predator

C.    Fish is usually afraid of predator                       

D.    The fish can catch the predator

16.    How do fish breathe in the water?

A.    They drink the water                                

B.    They absorb oxygen in the gills

C.    The gills passes through the water              

D.    They absorb oxygen in the water

17.    “One reason they do this is for protection.”

What does the underlined word refer to?

A.    The fish          

B.    The predators                 

C.    The groups                 

D.    The gills​