For each blank in the following passage there are four words or phrases marked A, B, C and D.Fill in each blank with the word or phrase that best fits the context.
Have you ever heard of cryosurgery? Cryosurgery involves freezing tissues to extremely cool temperatures.It is a procedure in which 1 body tissues are destroyed by 2 them to extremely cold temperatures.The temperatures used range from -150℃to absolute zero.The surgical procedure freezes unhealthy tissue, and the freezing destroys the 3 .For external injuries, liquid nitrogen(氮), which has a temperature of -196℃, is applied 4 to the cells.For 5 tumors(肿瘤), liquid nitrogen is circulated 6 an instrument called a cryoprobe(冷冻探针), a low-temperature scalpel or probe cooled by liquid nitrogen.
How does cryosurgery destroy cells?The ice created by the liquid nitrogen will destroy nearly all cells it 7 in contact with.As ice forms around a cell, the free water inside the cell is 8 .This causes the cell to shrink and the walls or membranes inside the cell to collapse.Poisonous proteins or chemicals within the cell are released. 9 , as the ice around shrunken cells begins to 10 , large amounts of free water rush back inside the cells, causing them to burst.The dead cells are then removed through normal 11 process.
How well does cryosurgery work? The 12 has proved successful in removing hemorrhoids some tumors.Cryosurgery may be used 13 to remove freckles(for cosmetic reasons)and to treat some skin cancers.It is also used in the treatment of bone cancer to freeze internal bone cavities.Cryosurgery has evolved from the 14 attempts to freeze tissue with a salt-ice mixture in the 1850s to the complicated cryoprobe method used today.Despite its success, side effects from cryosurgery tend to be worse if it is done in men who have already had radiation 15 , and therefore this kind of new surgery is not fit for everyone.