Leukemia

　　Leukemia is the most common type of cancer kids get, but it is still very rare. Leukemia involves the blood and blood-forming organs, such as the bone marrow.___1___

　　A kid with leukemia produces lots of abnormal white blood cells in the bone marrow. Usually, white blood cells fight infection, but the white blood cells in a person with leukemia don’t work the way they’re supposed to. ___2___The abnormal white blood cells multiply out of control1, filling the bone marrow and making it hard for enough normal, infection-fighting white blood cells to form. Other blood cells — such as red blood cells (that carry oxygen in the blood to the body’s tissues) and platelets (that allow blood to clot) — are also crowded out2 by the white blood cells of leukemia. These cancer cells may also move to other parts of the body, including the bloodstream, where they continue to multiply and build up3.

　　Although leukemia can make kids sick, most of the time it is treatable, and kids get better. Almost all leukemia patients are treated with chemotherapy, which means using anti-cancer drugs.

　　___3___Chemotherapy quickly goes to work, traveling through the blood to the bone marrow. There, the drugs can attack the cancer cells. After several weeks of chemotherapy, many kids begin to feel better.

　　Some children with leukemia will also have to have radiation therapy, too. ___4___

　　If the cancer isn’t getting better from using the usual amounts of chemotherapy and radiation, then kid with leukemia will probably need more treatment —with higher doses of chemotherapy and radiation to finally kill the cancer cells. But this heavy-duty treatment will also harm the normal cells in the kid’s bone marrow too, and the bone marrow will no longer be able to produce normal blood cells. So, doctors will then give a kid — or anyone else with bone marrow that is no longer working — normal bone marrow tissue from someone else who is healthy. ___5___

　　练习：

　　A. The chemotherapy drugs are given through a catheter, a narrow tube that is inserted into a blood vessel, sometimes in the kid’s upper chest.

　　B. Early symptoms of leukemia are often overlooked, since they may resemble symptoms of the flu or other common diseases.

　　C. This is a special procedure called a bone marrow transplant, and it helps the patient make new blood cells so they can recover from the leukemia.

　　D. Bone marrow is the innermost part of some bones where blood cells are first made.

　　E. They don’t protect the person from infections very well.

　　F. Radiation therapy uses invisible high-energy waves (similar to X-rays) to kill cancerous cells.

　　答案与题解:

　　1.D　前一句提到，白血病涉及血液和造血器官，如骨髓。接下来应首选阐释骨髓的句子。

　　2.E　前一句讲，通常情况下，白细胞会对抗感染，但是白血病病人身上的白细胞却发挥不了其应当发挥的作用。这意味着它们不能很好地保护病人免受感染的侵袭。

　　3.A　前一句涉及化学疗法，即抗癌药物的使用。接下来应首选表达如何使用化疗药物的句子。

　　4.F　前一句讲到，有些患白血病的孩子也将接受放射治疗。接下来应选择能够说明放射治疗的句子。

　　5.C　此段的主要意思是，接受大剂量化疗的白血病患者骨髓可能出现问题，不再正常发挥作用。这时，医生就要把一个正常人的骨髓组织移到他身上。这一医疗措施的名称及其作用应该是下一句话所表达的内容。

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（实习编辑：高奕飞）