设随机变量X具有概率密度,则常数k=()。 A.0.2 B.0.3 C.0.4 D.

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问题:

设随机变量X具有概率密度,则常数k=()。

A.0.2

B.0.3

C.0.4

D.0.5

考点:注册环保师环保公共基础知识注册环保师公共基础知识
题型:单项选择题

阅读下面短文,按照句子结构的语法性和上下文连贯的要求,在空格处填人一个适当的词或使用括号中词语的正确形式填空,并将答案填写在答题卷为16-25的相应位置上。

Many accidents happened in our daily life, including the traffic, drowning, stampeding and so on, which caused many disasters. As a result,  16   ( person) safety lessons are very necessary.

Actually, more and more accidents took place around us,    17   (make) our personal safety under threat. Therefore, personal safety should be the priority to the students.

Having read the report    18  accidents that happened in China, I instantly think of the accident    19  occurred to me ten years ago. Like other naughty boys, I like doing sports, especially swimming.  It was a hot summer noon. I went out to swim with    20   neighbor without parents’ permission. Happy as we were, we even tried having a    21   (compete) to see who could swim     22  (fast) and farthest. In order to show my ability of swimming, I spared no effort to swim. I did not realize that I had no other strength left    23  I reach the middle of the river. I and my body was sinking into   24  bottom of the river.    25  , (fortune) with the help of my friends, I had a narrow escape. What an unforgettable experience! It was my showing off that caused the unnecessary accident.

This case is only one among several hundred terrible accidents that take place around us every day. It is high time that we realized the importance of personal safety. And only with a good sense of personal safety can we live a safe and happy life!

题型:单项选择题

曲线y=xex+2x+1在点(0,1)处的切线方程为 (    ).

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某精神卫生中心的社会工作者老程经常为本地区的居委会工作人员和社区居民举办讲座,以增进大家对精神疾病的了解,促进大家对精神疾病患者的接纳。根据社会工作领域的划分,老程开展的服务属于()。

A.心理健康服务

B.医疗社会工作

C.矫治社会工作

D.家庭社会工作

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—_______ your mobile phone number, Mr. Wang?

—13409964565. [ ]

A. What

B. What's

C. How's

D. Where's

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