Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks in the following questions.

Most people are afraid of sharks, but they usually do not know much about them. For example, there are about 350 species of sharks living in all oceans around the world. All of the sharks are carnivores, but most of them don't (27) ____________ people. Some sharks are very small while some others are very big.
The biggest species of sharks may be 60 feet long and weigh 15 tons. Unlike (28) ____________ other kinds of fish, sharks do not have bone. Their bodies are made up of a kind of tough white material (called cartilage). Sharks do not have ears. (29) ____________ they can ‘hear’ sounds and movements making water vibrate. The vibrations help sharks find food. Sharks use their large eyes to find food, too. Most sharks see best in low light. They often hunt for food at dawn, in the evening or in (30) _________ middle of the light.