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问题 单项选择题 A1/A2型题

关于放射防护，下列哪种说法是错误的（）

A.主动防护的目的是尽量减少X线的发射剂量

B.使用原子序数较高的物质材料阻挡X线属于屏蔽防护

C.限制照射范围，减少辐射量

D.原发射线比继发射线的能量大，对放射工作者的影响也大

E.放射工作者最简易的防护措施是距离防护

答案

参考答案：D

解析：放射防护包括主动防护和被动防护，主动防护为了尽量减少X线的发射剂量，被动防护的目的是使受检者尽可能少接受射线剂量，包括屏蔽防护和距离防护。继发射线比原发射线的能量虽小但易被吸收，对放射工作者的影响也大。

解答题
已知f（x）是定义在[-1，1]上的函数，且f（x）=f（-x），当a，b∈[-1，0]，且a≠b时恒有[f（a）-f（b）]（a-b）＞0，f（0）=1，f(
1
4
)=
1
2
．
（1）若f（x）＜2m+3对于x∈[-1，1]恒成立，求m的取值范围；
（2）若2f(2x-
1
4
)＞1，求x的取值范围．
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单项选择题

Valentine’s Day was the time my father chose to show his love for the special people in his life. Over the years I fondly thought (31) him as my "Valentine man".

My first recollection of the magic he could bring to Valentine’s Day came when I was six. That morning at the breakfast table I found a card and a gift-wrapped package at my chair. The card was (32) "Love, Dad" and the gift was a ring with a small piece of red glass to represent my birthstone, a ruby.There is (33) difference between red glass and rubies to a child of six, and I remember wearing that ring with pride that all the cards in the world (34) not surpass.

As I grew older, the gifts gave (35) to heart-shaped boxes filled with my favorite chocolate and always included a (36) card signed "Love,Dad". In those years my thank-you became more of a perfunctory response. The cards seemed less (37) , and I took for granted that the Valentine would always be there. I had (38) my hopes and dreams in receiving cards and gifts from "significant others" and "Love, Dad" just didn’t seem quite enough.His final card remains on my desk today. It’s a (39) of how special fathers ean be and how important it has been to me over the years to know that I had a father who continued a tradition of love with simple acts of understanding and an ability to express happiness over the people in his life.Those things never (40) , nor does the memory of a man who never tried being my Valentine.

34（）。

A. could

B. did

C. must

D. should
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