四级听力复合听写模拟训练第15套_大学英语听力

四级听力复合听写模拟训练第15套

　　chemicals to destroy the cancer.

　　So, the researchers designed a two-part nanocell. The cell is in nanometers, or one thousand millionth of a meter.

　　The scientists say it was small enough to pass through the blood vessels of the cancer, but it was too big to enter normal blood vessels. The surface of the nanocells also helped them to avoid natural defenses.

　　That cut off the blood supply and trapped the nanocell inside the cancer. Then, the nanocell slowly released chemotherapy drugs to kill the cancer cells.

　　Section C

　　Scientists have developed a new cancer drug. So far, they have tested it only on laboratory animals. The drag is designed to invade and kill cancer cells but not healthy cells.

　　First, the drug enters the cancer and destroys the supply of blood. Then it releases poison to destroy the cancer cells.

　　Researchers at the Massachusetts Institute of Technology in Cambridge carried out the study. The results appeared in Nature magazine. A school news release called the drug an anti-cancer smart bomb.

　　Ram Sasisekharan is a professor at M.I.T. He says his team had tosolve three problems. They had to find a way to destroy the blood vessels, then to prevent the growth of new ones. But they also needed the blood vessels to supply chemicals to destroy the cancer.