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问题 不定项选择题

下列对露置在空气中已部分变质的氢氧化钠溶液样品进行的相关实验中，实验现象及结论合理的是[ ]

A．取少量溶液样品，滴入氯化钡溶液，有白色沉淀生成

B．取一定量溶液样品，滴入稀盐酸，立即有大量气体产生

C．取一定量溶液样品，滴入适量的澄清石灰水，过滤，向滤液中滴加酚酞溶液，溶 液变红，证明原样品中含有氢氧化钠

D．向溶液样品中加入适量的澄清石灰水至恰好完全反应，过滤，可除去样品中的杂质

答案

AD

单项选择题

A tree’s age can be determined by counting the annual growth rings in its trunk. Each ring represents one year, and the ring’s thickness reveals the relative amount of rainfall that year. Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk. Each tomb was constructed from freshly cut logs, and the tombs’ builders were constrained by tradition to use only logs from trees growing in the sacred Pazyryk Valley.
Which one of the following, if true, contributes most to an explanation of the archaeologists’ success in using annual rings to establish the relative ages of the tombs at the Pazyryk site ？（）

A．The Pazyryk tombs were all robbed during ancient times, but breakage of the tombs’ seals allowed the seepage of water, which soon froze permanently, thereby preserving the tombs’ remaining artifacts.

B．The Pazyryk Valley, surrounded by extremely high mountains, has a distinctive yearly pattern of rainfall, and so trees growing in the Pazyryk Valley have annual rings that are quite distinct from trees growing in nearby valleys.

C．Each log in the Pazyryk tombs has among its rings a distinctive sequence of twelve annual rings representing six drought years followed by three rainy years and three more drought years.

D．The archaeologists determined that the youngest tree used in any of the tombs was 90 years old and that the oldest tree was 450 years old.

E．All of the Pazyryk tombs contained cultural artifacts that can be dated to roughly 2300 years ago.
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单项选择题

哪一项不是髓母细胞瘤的CT表现（）

A.梗阻性脑积水

B.肿瘤明显强化

C.瘤周水肿

D.脂肪密度

E.主要发生于小脑蚓部
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