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问题 选择题

如图，先用绳子把一个铁锁悬挂起来，然后把铁锁拉起，松手后，铁锁向前摆动又摆回来（不计阻力），有关铁锁在摆动过程中的能量转化，下列说法正确的是（　　）

A．铁锁下降过程中，重力势能转化为动能

B．铁锁上升到最高点，重力势能最小

C．铁锁下降到最低点，动能最小

D．铁锁在摆动过程中机械能逐渐增大

答案

答案：A

A、铁锁下降过程中，重力势能转化为动能，故该选项符合题意；

B、铁锁上升到最高点，重力势能最大，动能为零，故该选项不符合题意；

C、铁锁下降到最低点，质量不变，高度最小，重力势能最小．质量不变，速度最大，动能最大，故该选项不符合题意；

D、铁锁在摆动过程中机械能逐渐减小，因为有小部分机械能转化成内能，故该选项不符合题意．

故选A．

判断题

《国际贸易术语解释通则》是在国际贸易长期的实践中逐渐形成的，属于任意性国际惯例。
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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.

11（）

A.why

B.when

C.wherever

D.whereas
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