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问题 选择题

对常温下pH=3的CH3COOH溶液，下列叙述不正确的是

A．

B．加入少量CH3COONa固体后，c（CH3COO—）降低

C．该溶液中由水电离出的c（H+）是1.0×10-11 mol／L

D．与等体积pH =11的NaOH溶液混合后所得溶液显酸性

答案

答案：B

题目分析：A、根据电荷守恒，可得，正确；B、加入少量CH3COONa固体后，尽管醋酸的电离平衡逆向移动，但c（CH3COO—）升高，错误；C、pH=3的CH3COOH溶液，c(H+)=0.001mol/L，则c(OH－)= 1.0×10-11 mol／L，水电离的c(H+)= c(OH－)= 1.0×10-11 mol／L，正确；D、pH=3的CH3COOH溶液与等体积pH =11的NaOH溶液混合，醋酸的浓度大于氢氧化钠溶液的浓度，所以混合后醋酸过量，溶液呈酸性，正确，答案选B。

填空题

世界各地几乎都有水晶产出，我国主要产（）水晶。
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单项选择题

Young girls at high risk for depression appear to have a malfunctioning reward system in their brains, a new study suggests. The finding comes from research that (1) a high-risk group of 13 girls, aged 10 to 14, who were not depressed but had mothers who (2) recurrent depression and a low-risk group of 13 girls with no (3) or family history of depression. Both groups were given MRI brain (4) while completing a task that could (5) either reward or punishment.

(6) with girls in the low-risk group, those in the high-risk group had (7) neural responses during both anticipation and receipt of the reward. (8) , the high-risk girls showed no (9) in an area of the brain called the dorsal anterior cingulated cortex (背侧前扣带皮质), believed to play a role in (10) past experiences to assist learning.

The high-risk girls did have greater activation of this brain area (11) receiving punishment, compared with the other girls. The researchers said that this suggests that high-risk girls have easier time (12) information about loss and punishment than information about reward and pleasure.

"Considered together with reduced activation in the striatal (纹状体的) areas commonly observed (13) reward, it seems that the reward-processing system is critically (14) in daughters who are at elevated risk for depression, (15) they have not yet experienced a depressive (16) ," wrote Ian H. Gotlib, of Stanford University, and his colleagues. " (17) , longitudinal studies are needed to determine whether the anomalous activations (18) in this study during the processing of (19) and losses are associated with the (20) onset of depression," they concluded. The study was published in the April of the Archives of General Psychiatry.

6（）

A.Made

B.Regarded

C.Insisted

D.Compared
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