问题 选择题

下列实验操作“先”,“后”顺序不正确的是(  )

A.实验室制氧气结束时,先移导管,后熄灭酒精灯

B.点燃一氧化碳前,要先检验其纯度,而后才能点燃

C.做CO还原氧化铜结束时,先停止通CO,后熄灭酒精灯

D.做气体制备实验时,先检查装置的气密性,后装药品

答案

A、先将导管从水槽中取出,再熄灭酒精灯,故A正确;

B、为防止不纯的一氧化碳点燃可能会发生爆炸,先检验其纯度,而后才能点燃,故B正确;

C、为防止爆炸和生成的铜又被氧化,应先停止加热,继续通一氧化碳至冷却,故C错误;

D、先检查制氧装置的气密性,再装药品,否则会浪费药品,故D正确.

故选C.

阅读理解

阅读理解

     Can dogs and cats live in perfect harmony in the same home? People who are thinking about adopting a dog as a friend for their cat are worried that they will fight.A recent research has found a new recipe for

success.According to the study, if the cat is adopted before the dog, and if they are introduced when still

young (less than 6 months for cats, a year for dogs), it is highly probable that the two pets will get along

swimmingly.Twothirds of the homes interviewed reported a positive relationship between their cat and dog.

However, it wasn't all sweetness and light.There was a reported coldness between the cat and dog in 25% of the homes, while aggression and fighting were observed in 10% of the homes.One reason for this is

probably that some of their body signals are just opposite.For example, when a cat turns its head away it

signals aggression, while a dog doing the same signals submission.

     In homes with cats and dogs living peacefully,  researchers observed a surprising behavior.They are

learning how to talk in each other's language.It is a surprise that cats can learn how to talk 'Dog', and dogs can learn how to talk 'Cat'.

     What's interesting is that both cats and dogs have appeared to develop their intelligence.They can learn to read each other's body signals, suggesting that the two may have more in common than was previously

suspected.Once familiar with each other's presence and body language, cats and dogs can play together,

greet each other nose to nose, and enjoy sleeping together on the sofa.They can easily share the same

water bowl and in some cases groom (梳理) each other.

     The significance of this research on cats and dogs may go beyond pets-to people who don't get along,

including neighbors, colleagues at work, and even world superpowers.If cats and dogs can learn to get

along, surely people have a good chance.

1. The underlined word "swimmingly" in Paragraph 1 is closest in meaning to ________.

A. early                                                                              

B. sweetly                                                                            

C. quickly                                                                            

D. smoothly                                                                          

2. Some cats and dogs may fight when ________.                                        

A. they are cold to each other                                                        

B. they look away from each other                                                    

C. they misunderstand each other's signals                                            

D. they are introduced at an early age                                                

3. What is found surprising about cats and dogs?                                      

A. They eat and sleep together.                                                      

B. They observe each other's behaviors.                                              

C. They learn to speak each other's language.                                        

D. They know something from each other's voices.                                      

4. It is suggested in Paragraph 4 that cats and dogs ________.                        

A. have common interests                                                              

B. are less different than was thought                                                

C. have a common body language                                                        

D. are less intelligent than was expected                                            

问答题 简答题