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. 

Going Inside Black Holes

     One of the strangest phenomena in the universe is the black hole. For years, scientists have studied black holes in an (39) ______ to better understand how they function. Like vacuum cleaners, black holes will suck up anything (40) ______ crosses their path. The incredible sucking power that black holes generate comes from gravity. They can quickly swallow up anything including planets, space debris, and anything else imaginable. Even light cannot escape the (41) ______ of black holes. Since they are able to pull in light, black holes are nearly impossible to see even with high-powered telescopes. (42) ______, scientists are able to detect the presence of black holes in space because of their effect on an observed area. 

     Black holes can originate in a few ways. One type of black holes occurs when a star comes to the end of its lifecycle and it dies in a supernova explosion. They can also occur when the mass of a neutron star becomes so great that it collapses in on itself. Black holes may also occur when several large and dense stars collide with one (43) _____in space. 

For years, scientists have studied black holes in an (39) ______ to better understand how they function.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 44 to 48.

Sylvia Earle is an underwater explorer and marine biologist, who was born in the USA in 1935. She became interested in the world's oceans from an early age. As a child, she liked to stand on the beach for hours and look at the sea, wondering that it must be like under the surface. When she was 16, she finally got a chance to make her first dive. It was this dive that inspired her to become an underwater explorer. Since then, she has spent more than 6,500 hours under water, and has led more than seventy expeditions worldwide. She has also made the deepest dive ever, reaching a record-breaking depth of 381 meters.

In 1970, she became famous around the world when she became the captain of the first all-female team to live under water. The team spent two weeks in an underwater "house". The research they carried out showed the damage that pollution was causing to marine life, and specially to coral reefs. Since then she has written several books and magazine articles in which she suggests ways of reducing the damage that is being done to the world's oceans. One way, she believes, is to rely on fish farms for seafood, and reduce the amount of fishing that is done the out at sea.

(Adapted from Complete IELTS by Rawdon Wyatt)

By then, the elite performers had all totaled 10000 hours of practice over the (43) ________of their lives, the merely good students 8000 hours and the future music teachers just over 4000 hours.