如图所示为研究气体扩散的实验装置,两个瓶中分别装有二氧化氮气体和空气,其中二氧化

题型:实验题

问题:

如图所示为研究气体扩散的实验装置,两个瓶中分别装有二氧化氮气体和空气,其中二氧化氮气体的密度大于空气的密度,为了增强实验的可信度,下面一只瓶里应装入____________气体,扩散实验说明了_____________________。

考点:扩散现象
题型:实验题
计算:
12
-(
3
3
-1+
3
(
3
-1)
-20130-|
3
-2
|
题型:实验题

水牛:牲畜:乡村

A.小鸟:鸣叫:树林

B.生物:鱼虾:湖水

C.台灯:书本:书桌

D.母鸡:家禽:打谷场

题型:实验题

阅读理解。

     Topping the class academically was certainly an advantage. Studying was a breeze for Nigel. The

reward was certainly incomparable to the little effort that he had to put it. It begin when he was selected

to help the teachers in the computer laboratories.

     The peak of his school career came not when he topped the school but when he was selected for the

nationwide competition. Unlike everyone else, Nigel wanted to join the contest because he liked playing

with the Lego sets and making something out of them. Nigel spent the next two months rebuilding the

robot. It was during the time that Nigel found out about the prizes for the competition. Its well us auspices

competitor. Alicia, from a neighboring school. His early intentions were forgotten. Getting the

thousand-dollar prize was more important than anything else. Nigel decided to befriend Alicia. Unaware of

his intentions, she told him all about the robot that she had been building for the competition. He even helped

her to put the finishing branches to her robot. He was glad with the way things had progressed. His robot

looked even better than Alicia's and it was able to become a ball with its arms, something Alicia had failed to

do.

      On the day of the competition, he says Alicia. Everything dawned on her the minute she saw him among

the competition. She stared at him, puzzled at first, then angry and finally a look of helplessness came over

her.

     The flashbulbs of the camera exploded in Nigel's try. The robot bird performed actions so unique and

different that the specialist judgments were the same. Nigel was so personal with himself that he did not

even notice the girl standing a few feet away from him. Without her, he would never win the competition.

1. What reward did Nigel receive for doing well in his school work?

A. He was offered a part-time job

B. He was honored with a scholarship

C. He helped his teacher construct a robot

D. He helped in the computer laboratories

2. Nigel's original intention of joining the contest was to ___.

A. be the top student of the school

B. being great honor to his school

C. constructs a robot with the Lego sets

D. wins the thousand-dollar prize

3. Why did Nigel help Alicia finish her robot?

A. He tried to make friends with her

B. He was fond of building robots

C. He intended to help her

D. He didn't want her to suspect him

4. What is the author's attitude towards Nigel's actions?

A. He is mildly critical

B. He is strongly critical

C. He is in favor of them

D. His attitude is not clear

题型:实验题

简述公文签收的含义及作用。

题型:实验题

下列各项符合国内特快专递邮件出口验单缮发规定的选项有()。

A.经主管人员签发

B.按顺序编号,每年换编

C.作为特快专递邮政公事寄发

D.所述事由清楚

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