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某 * * 票规定:从01到36共36个号中抽出7个号为一注,每注2元.某人想先选定吉利号18,然后从01至17中选3个连续的号,从19至29中选2个连续的号,从30至36中选1个号组成一注.若这个人要把这种要求的号全买下,则至少要花多少元钱?

答案

2100

先分三步选号,再计算总钱数.

按号段选号,分成三步.

第一步从01至17中选3个连续号,有15种选法;

第二步从19至29中选2个连续号,有10种选法;

第三步从30至36中选1个号,有7种选法.

由分步乘法计数原理可知,满足要求的号共有

15×10×7=1050(注),

故至少要花1050×2=2100(元).

单项选择题

普惠制原产地证明书：FORM A原产地标准栏目，如果出口商品完全是出口国自产的，不含有进口成分，出口到所有给惠国，填写________。 ( )

A．“W”

B．“P”

C．“Y”

D．“F”
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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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