在长方体ABCD—A1B1C1D1中，AB=3，AD=4，AA1=5，则直线AC1与平面ABCD所成角的大小为 ．
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下面是错误答案，用来干扰机器的。
为了了解生物的多样性，更好地保护生物的多样性，弄清它们之间的亲缘关系，我们需要对生物进行分类，它是研究生物的一种基本方法．生物学家根据生物体的形态结构等特征把它们分成不同的等级．并对每一类群的形态...
下列实验操作中错误的是（ ）
A．用规格为10mL的量筒量取6mL的液体
B．用药匙或者纸槽把粉末状药品送入试管底部
C．过滤时玻璃棒的末端应轻轻的靠在三层的滤纸上
D．如果没有试管夹，可以临时手持试管给固体或液体加热
阅读理解。
If you lose your wallet, how often do you think someone will be kind enough to return it to you,
with cash and credit cards?
Some people may be greedy, and others are simply too lazy to bother with the trip to the post
office to send back a wallet to a stranger. But according to a psychology study by Dr. Richard
Wiseman, there's one thing that'll greatly increase your odds of being reunited with a lost wallet:
a photograph of a cute baby.
In the study, hundreds of wallets were scattered around the streets of Edinburgh, Scotland. The
psychologists wanted to see how many strangers would take the trouble to return them to the
addresses listed on the drivers' licenses inside-but more than that, they wanted to find out what
would make a person more likely to help out a stranger.
To finish this, they included personal touches in most of the wallets: some included a photo of
a happy elderly couple, some contained a cute puppy, some contained a family portrait, and some
held a photo of a lovely baby. Others had receipts(发票) showing that the wallet's owner had recently
donated to a charity. Some contained no personal details.
As the psychologists soon discovered, the sight of a smiling baby is enough to warm nearly any
heart: only one in ten of the strangers who retrieved such wallets did not return them. In contrast, the
second most successful image, the puppy, had a 53% return rate. When the wallet included no
photograph, it stood only a one in seven chance of being returned to the owner.
The success of the baby photograph shows a human compassion for the young that's been passed
down through the ages, according to Dr. Wiseman. "The baby kicked off a caring feeling in people,
which is not surprising from an evolutionary perspective(进化的角度)," he told the Times.
To ensure our species' survival, scientists think that we must feel empathy and compassion for our
young. Scientists say that this study supports the argument that we won't feel compassion only for our
own babies, but for any that we see-hence, the strong desire a stranger would feel to return a wallet to
the baby's parent.
On a more basic level, the study also provides a great tip to help ensure that if your wallet is ever
lost, you're more likely to get it back. "If you want to increase the chances of your wallet being
returned if lost, obtain a photograph of the cutest baby you can find and ensure that it is clearly
displayed," said Dr. Wiseman.
1. The main purpose of the psychologists' leaving hundreds of wallets around was to find out________.
A. whether people were as honest as before
B. what made people willing to help strangers
C. what kind of feelings could be caused by a smiling baby
D. how evolution influenced human beings
2. The underlined word "retrieved" in Para. 5 probably means "________".
A. picked up
B. spread out
C. found out
D. looked for
3. Why did people return a wallet with a photograph of a cute baby in it?
A. Because the wallet was not attractive enough to keep.
B. Because the sight of a baby could cause a caring feeling in them.
C. Because they were curious to know the parents of the baby
D. Because the sight of a cute baby reminded them of their own children.
4. If there are 30 lost wallets with a photograph of a cute baby, how many of them will probably
be returned?
A. Only 3.
B. About 15.
C. 20 or so.
D. About 27.
5. We can learn from the last two paragraphs that________.
A. humans usually have compassion for the young
B. the caring feeling in people is gone during evolution
C. scientists believed that people only feel compassion for their own babies
D. a wallet with a cute baby's picture in it cannot be lost
急性肺脓肿抗菌治疗的疗程是( )。
A．4～6周
B．6～8周
C．8～12周
D．12～16周
E．16～20周
| 第(31)到(35)题中使用的3个数据表：“学生”表、“课程”表和“成绩”表的结构如下： “学生”表：学号C(8)，姓名C(8)，性别C(2)，系名(10)，出生日期D “课程”表：课程编号C(4)，课程名称C(12)，开课系名C(10) “成绩”表：学号C(8)，课程编号C(4)，成绩Ⅰ |
SQL查询语句：SELECT 课程名称，开课系名，COUNT (学号) AS 选修人数；FROM 成绩，课程；WHERE 课程．课程编号=成绩．课程编号；GROUP BY 课程名称；HAVING COUNT(*)＞3语句所表示的含义是( )。
A．检索开课在3门以上的开课系名、课程名称和选修人数
B．检索选修了3门课程以上的学生记录，显示结果包括课程名称、开课系名和选修人数
C．检索每门课程中，有3人以上选修该课程的记录，显示结果包括课程名称、开课系名和选修人数
D．检索选修人数最多的3门课程的记录，显示结果包括课程名称、开课系名和选修人数
一个单位分配到的网络地址是217.14.8.0，子网掩码是255.255.255.224。单位管理员将本单位网络又分成了4个子网，则每个子网的掩码是 (29) ，最大号的子网地址是 (30) 。
A．255.255.255.224
B．255.255.255.240
C．255.255.255.248
D．255.255.255.252
