长度为L=0.5m的轻质细杆OA ，A端有一质量为m=3.0kg的小球，如图所示

人体中没有正常菌群存在的部位是（）

A.生殖道

B.咽喉

C.血液

D.鼻腔

E.肠道

下列关于热现象的解释错误的是（　　）

A．高压锅是利用液体的沸点随气压增大而升高的原理工作的

B．高空中的冰晶下落变成雨滴时发生的是熔化现象

C．雪灾时在马路上洒盐是为了降低积雪的熔点

D．炒菜时冒出的“白气”是汽化后的水蒸气

根据短文内容和所给中文提示，在空白处填入单词。每空限填一词。

US President Obama gave a TV speech to his country’s students on the 小题1: (第一) day of school. He made it from a    小题2:  (教室) in a high school. He told them to study as   小题3: (努力) as they could.

“NO matter(无论) what you want to do with your life, you will need an education, ” he said.

“This isn’t just important for your own life and your own future. It will  小题4:  (决定) the future of this county.”

Obama also said that school is not always   小题5: (容易). The challenges (挑战) of life make school a difficult time.

“Maybe you can’t get your Parents’  小题6:(帮助). Maybe someone   小题7: (要求) you to go something wrong. But there is no excuse for not doing your homework of for not   小题8: (尝试). Your attitude(态度) toward yourselves and your education is  小题9: (最) important.”

Students shook  小题10:  (手) with Obama at the end of the class.

在正态分布条件下，B=±3б其出错机会是多大？

在我国公民的基本权利中，公民参与国家管理的基础和标志是（）。

A.公民行使监督权

B.选举权和被选举权

C.基层民主自治权

D.政治自由