Complete the summary.

Choose NO MORE THAN THREE WORDS from the passage for each answer.

Write your answers in boxes 37-40 on your answer sheet

The blood’s duty in the human body is definitely irreplaceable. Two of its main functions are to transport (37) …………..……. throughout the body and to carry substances that are necessary to help us grow and become strong. However, there are times when the blood cannot distribute oxygen properly; surrogate blood is needed to do the task. In this situation, the substitute is called (38) …………..……. .This sounds good for others; however, there are some serious controversies related to this medical breakthrough. Blood surrogates in development, like HBOCs and PFCs, had caused heart attacks and had even (39) …………..……. during clinical tests. But new alternatives are being studied to hopefully aid doctors in surgical procedures in the future. For example, it would be possible to use these blood substitutes to cure (40) …………..…….