有下列事实:①干冰升华 ②水蒸发③水电解成氢气和氧气 ④氧化汞受热生成汞和氧气.

题型:选择题

问题:

有下列事实:①干冰升华 ②水蒸发③水电解成氢气和氧气 ④氧化汞受热生成汞和氧气.其中能说明“分子可以分成原子”的是(  )

A.①和③

B.③和④

C.①和④

D.②和③

考点:分子的定义原子的定义
题型:选择题

以下是我们熟悉的几种气体,其中可用如图所示装置气体碱石灰(NaOH与CaO的混合物)干燥并收集的是省略了铁架台等仪器)(  )

①H2  ②O2  ③CO2  ④SO2⑤CH4   ⑥NH3

A.①②

B.③④

C.①⑤

D.①⑤⑥

题型:选择题

阅读理解。

阅读下面短文,并根据短文后的要求答题。(请注意问题后的词数要求)

       Psychology (心理学) tells us that many people hate to take risks. But it is good for us to take risks,

especially when the risk is to achieve a desired result. In that way, we become stronger and braver.

     Our human nature should be to take risks, but some people just sit and wish they didn't have the fear to move on.This is because of one or two failures in their lives. Please step out and don't let the past hold you back from living life to the fullest. Move forward and move on!

      In studying the psychology of taking risks, we find that human nature provides us with the desire to

experiment and take chances.

     Risk taking is a great benefit that allowed our ancestors ( 祖先) to become stronger and stronger day

by day. By taking risks they fought off enemies and discovered new land. This attitude has become a part of our modem culture.Riding a roller coaster is a common risk taking activity that even the average person seems to enjoy although they have the understanding that it is dangerous.

      Getting in a car each day is a risk. Getting out of bed is a risk. We need to take risks so that we can

finish many things. Astronauts take risks when they get inside a rocket; however, the things they achieve

are great. Businessmen take a risk when they buy parts of a company. However, without doing that, they

could not make more money.

     We need to take risks so that we can gain something. It is impossible to move forward in life, earn

money, enjoy a relationship, play a sport, or do anything else____. It is all part of the game. It's one of the most important parts of life.

1.  What is the main idea of the passage? ( Please answer within 10 words)

__________________________________________________________

2. Which sentence in the passage can be replaced by the following one?

   Don't let the failures that you have experienced prevent you from taking risks and living a meaningful life.

__________________________________________________________

3. Please fill in the blank in the last paragraph with proper words or phrases to complete the sentence.  

( Please answer within 10 words)

__________________________________________________________

4. Why do people ride a roller coaster although they know it is dangerous? ( Please answer within 10

words)

__________________________________________________________

5. Translate the underlined sentence in the first paragraph into Chinese.

__________________________________________________________

题型:选择题

以下四种条件中,哪个条件不是引起煤气爆炸的必要条件()。

A、混合气体达到爆炸范围;

B、必须有明火、电火达到着火温度;

C、混合气体压力必须大于大气压;

D、混合气体处于密闭容器或相当于密闭容器内。

题型:选择题

为了迎接下个月的体操比赛,一体操教练正在制订一周工作计划。从周一至周五每一个单独辅导时间内给六个学生——H、I、K、O、U、Z中的每一个上课。除了在某一天该教授在两个分开但连续的辅导时间给两个学生上课之外,在其余的每一天都只辅导一个学生。下面是该教授一周的工作计划所遵循的原则:
(1)H在Z之前。
(2)I的课在周四。
(3)K和O的课紧密相连,且K和O不能在同一天。
(4)周一和周三只有一个学生上课。

把Z的课安排在下面哪一天就可以完全确定U的上课时间

A.周一

B.周二

C.周三

D.周四

题型:选择题

首次公开发行股票的持续督导期间为股票上市当年剩余时间及其后两个完整会计年度,自股票上市之日起计算。( )

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