问题 单项选择题

当前目录是用户当前工作的目录,下列关于当前目录的叙述中正确的是( )。 Ⅰ.在当前目录下,可以采用相对路径名查找文件 Ⅱ.当前目录放在内存 Ⅲ,每个用户有一个当前目录 Ⅳ.当前目录可以改变

A.Ⅰ、Ⅱ

B.Ⅰ、Ⅱ、Ⅲ

C.Ⅰ、Ⅱ、Ⅳ

D.Ⅰ、Ⅱ、Ⅲ、Ⅳ

答案

参考答案:D

解析:[分析] 若从当前目录开始查找文件,路径名只要给出从当前目录开始到所要访问文件的相对路径名即可,这样检索路径所需时间缩短,检索速度提高;如果需要,用户可随意更改当前目录;为了提高速度,当前目录放在内存,并且每一个用户都有一个自己的当前目录。

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.

7()

A.per

B.weaker

C.lower

D.higher

多项选择题