某种原子核X经过α衰变后变为原子核Y，再经过β衰变后变为原子核_爱下问搜题

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问题多选题

某种原子核X经过α衰变后变为原子核Y，再经过β衰变后变为原子核Z，即

ab

X

α

cd

Y

β

ef

Z，下列关系中正确的是（　　）

A．a=e+4

B．c=-1+e

C．d+1=f

D．b=f+1

答案

α衰变的过程中电荷数少2，质量数少4，则c=a-4，d=b-2．

β衰变的过程中，电荷数多1，质量数不变，则e=c，f=d+1．

则a=e+4，c=e，d+1=f，b=f+1．故A、C、D正确，B错误．

故选ACD．

完形填空

When we read books we seem to enter a new world. This new world can be similar to the one we are living in, or it can be very      . Some stories are told       they were true. Real people who live in a       world do real things; in other words, the stories are about people just like us doing what we do. Other stories, such as the Harry Potter books, are not       . They are characters and creatures that are very different from us and do things that would be       for us.
But there is more to books and writing than this. If we think about it, even realistic writing is only     . How can we tell the difference between what is real and what is not real? For example, when we read about Harry Potter, we       seem to learn something about the real world. And when Harry studies magic at Hogwarts, he also learns more about his real life than      . Reading, like writing, is an action. It is a way of      . When we read or write something, we do much more than simple look at words on a page. We use our       -- which is real-- and our imagination-- which is real in a different way --- to make the words come to life in our minds.
　　Both realism and fantasy(幻想)       the imagination and the “magic” of reading and writing to make us think. When we read       realistic, we have to imagine that the people we are reading about are just like us, even though we       that we are real and they are    . It sounds       , but it works. When we read, we fill in missing information and     about the causes and effects of what a character does. We help the writer by   52  that what we read is like real life. In a way, we are writing the book, too.
Most of us probably don’t think about what is going on in our       when we are reading. We pick up a book and lose       in a good story, eager to find out what will happen next. Knowing how we feel       we read can help us become better readers, and it will help us discover more about the real magic of books.

D．instructive

D．understanding

A．a newspaper

多项选择题

楚辞是公元前四世纪，我国战国后期的伟大诗人屈原创造的一种诗体。它（），灵活多变，有停顿、有延伸，委婉而多情致。

A.句子参差不齐

B.形式活泼自由

C.多用“兮”字

D.语句漫长流利