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问题 多项选择题

按照国家食品污染物年度监测计划规定的样品种类和数量采集监测所需样品在采样中要充分遵循以下哪些原则（）。

A.采集样品的代表性

B.典型性

C.适时性和可操作性

D.随机抽样

答案

参考答案：A, B, C, D

改错题
短文改错
       此题要求改正所给短文中的错误。对标有题号的每一行作出判断：
      如有错误(每行只有一个错误),则按下列情况改正：
      此行多一个词：把多余的词用斜线(\)划掉,在该行下边横线上写出该词,并也用斜线划掉。
      此行缺一个词：在缺词处加一个漏字符号,在该行下边横线上写出该加的词。
      此行错一个词：在错的词下划一横线,在该行下边横线上写出改正后的词。
      注意：原行没有错的不要改。
    
                
     Last weekend, I help my grandparents prepare their trip   
to Beidaihe. In Saturday morning, together with my grandparents,
I searched Internet for the train schedule, the weather in Beidaihe,  
and some hotel information. In the afternoon, I went back to the train 
station and managed to buy two ticket for my grandparents 
because there was a long queue. After dinner, I packed
the suitcase with the things their grandparents needed, such as clothes, 
glasses, a umbrella, and a map. The next morning, I went to 
the station to see them off. Waved goodbye to them on the 
platform, I felt happily for them and wished them a safe journey.   		1.________
2.________
3.________
4.________
5.________
6.________
7.________
8.________
9.________
10.________
                                                                                                                                                                                  
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单项选择题

称成釉细胞瘤为临界瘤的原因为（）

A.来源于牙源性上皮

B.长得特别大

C.瘤体内有牙根吸收

D.有局限性浸润生长

E.压迫三叉神经引起相应部位麻木
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