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问题 选择题

方程x2－4x＝0的解是

A．x＝4

B．x1＝1，x2＝4

C．x1＝0，x2＝4

D．x1＝1，x2＝－4

答案

答案：C

析：由题已知的方程进行因式分解，将原式化为两式相乘的形式，再根据两式相乘值为0，这两式中至少有一式值为0，求出方程的解．

解答：解：∵x2-4x=0，

∴x（x-4）=0，

∴方程的解：x1=0，x2=4．

故选C．

多项选择题 X型题

对积的诊断为排除恶性病变必须结合（）

A.B超

B.CT

C.MRI

D.病理组织活检

E.X线
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填空题

Today, we’ll talk about what other effects watching TV might produce on children. Children should be (1) a lot of television, many experts and parents agree, but there is at least one circumstance when it might be beneficial: (2) . A recent study conducted by Italian researchers found that children (3) immediately preceding and during blood tests experienced less pain than children whose mothers (4) during the procedure, or children whose mothers were present but (5) .
The research, led by Carlo Brown, MD, at the University of Siena, is published in the Archives of Disease in Childhood. (6) the study. None received any type of anesthesia; the children and their mothers (7) . Both the group whose mothers attempted to distract them from the blood tests and those whose mothers simply observed reported (8) than the group who watched cartoons. For that group, the levels of pain were less and the children were better able to (9) .
One of the possible explanations is that children might have (10) during the procedures, exacerbating their perception of pain. "The higher pain level reported by children during (11) shows the difficulty mothers have in interacting positively (12) in their children’s life," the authors write.
However, they stressed that (13) still provided benefits, noting that the children would (14) during the procedures. "Indeed, children state that having their parent present (15) when in pain," say the authors.
Another possibility offered for consideration is the notion that the (16) might release pain-quelling endorphins. Endorphins, (17) produced by the pituitary gland, resemble opiates in their ability to produce analgesia and a sense of well-being. In other words, they might (18) .
In any case, the study results suggest that health workers should (19) to watch television during painful procedures (20) .
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