下列内容中，好的抽样原则是（）1）没有偏移2）具有代表性3）层_爱下问搜题

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问题单项选择题

下列内容中，好的抽样原则是（）

1）没有偏移

2）具有代表性

3）层别

4）随机性

A、1和4

B、2、3和4

C、1、2和4

D、1、3和4

答案

参考答案：C

填空题

如果x：y=4：5，那么______×4=______×______．

填空题

Part 1

·Read the article below and choose the best sentence from the list on the next page to fill each of the gaps.
·For each gap (1-8) mark one letter (A-H) on the Answer Sheet.
·Do not mark any letter twice.

When the Young Take Their Lives

A few weeks ago, I received a particularly disturbing page. "A 22-year-old woman is in the emergency room with a gunshot wound to the head," my chief resident told me. (1) . The woman, a recent college graduate, was starting to show signs of brain death. Over the next several hours, we worked to preserve the life she had tried to throw away.
(2) . In the 30 years from 1950 to 1980, the annual suicide rate among college-age women has almost doubled, from 3.9 deaths per 100,000 to 7.0 per 100,000, while the rate among college-age men has tripled, from 10 per 100,000 to 32 per 100,000 a year. (3) .
Students kill themselves at all times of year, but attempted suicides begin to go up in the fall, according to the National Institute of Mental Health. Often the immediate cause seems to be a recent rejection, disappointment or academic failure.
(4) . Even trained mental-health professionals have made mistakes. But there are warning signs you can watch for in friends and loved ones, such as withdrawing from all social activities, dramatic changes in personality—including suddenly becoming much happier or calmer-significant shifts in sleeping or eating habits and giving away cherished personal items.
(5) . Studies of suicide survivors show that often just five minutes elapse from the time someone thinks about committing suicide until the actual attempt.
Finally, it is OK to come right out and ask friends or family members whether they are thinking of suicide. (6) . Be sure to let them know that they are not alone and that help is available through school counselors and mental-health hot lines, in hospitals and now online.
Through the years, I have treated many patients who have attempted suicide. (7) . Our 22-year-old patient is awake now and even talking a bit. I’m optimistic about her physical recovery but disquieted about her chances overall. (8) . What no one knows is whether we will be able to pick up the pieces one more time.

A. I do it with the sincere hope that they will get better
B. "Oh, and it looks self-inflicted," he added
C. The experts will tell you that having tried to kill herself once, she is at a greater risk of trying again
D. This year’s toll for adults aged 19 to 24 is expected to reach 1,000 deaths
E. Don’t get fooled into thinking that all people who commit suicide have carefully worked out a plan in advance
F. You won’t be giving them any ideas
G. Trying to determine whether a young person is suicidal can be difficult
H. Her predicament made me wonder, once again, what drives people to suicide and why young people resort to such a desperate measure