Read the text below and answer the questions.
 

   The polar bear is a very big white bear. We call it the polar bear because it lives inside the Arctic Circle near the North Pole. There are no polar bears at the South Pole. The polar bears live at the North Pole. There is only snow, ice, and water. There is not any land.

   These bears are three meters long, and weigh 450 kilos. They can stand up on their back legs because they have very wide feet. They can use their front legs like arms. The polar bears can swim very well. They can swim 120 kilometers out into the water. They catch fish and sea animals for food. They go into the sea when they are afraid.

   People like to kill the polar bears for their beautiful white coats. The governments of Canada, the United States, and Russia say that no one can kill polar bears now. They do not want all of these beautiful animals to die.

A polar bear can stand up on their back legs because ____