Warm water freezes more quickly than cold． Sir Francis Bacon said that almost four hundred years ago． But few people believed him - till 1970． In that year Canadian scientist George Kell proved the 题目和参考答案——青夏教育精英家教网—

题目内容

　　Warm water freezes more quickly than cold． Sir Francis Bacon said that almost four hundred years ago． But few people believed him - till 1970． In that year Canadian scientist George Kell proved the English scholar was right． Dr． Kell filled an open pail with cold water． He filled another with warm water． He exposed both to the same low temperature． The warm water froze first．

　　The lack of covers on the pails was the secret． Some of the warm water changed to vapor． It evaporated into the air． This meant that less of the warm water was left to freeze． And so the warm water froze faster than the cold water --- even though it had a greater temperature drop to make．

1．Sir Francis Bacon was_______．

A．an American experimenter　　B．a Canadian scientist

C．an English scholar D．an Australian writer

2．Most people didn't believe Bacon because warm water is________．

A．somewhat heavier than cold water

B．able to flow faster than cold water

C．further from freezing temperature than cold water

D．quicker to evaporate than cold water

3．Dr． Kell's pails were both_________．

A．filled with water　　 B．left uncovered

C．exposed to the same temperature D． All of the above

4．The second paragraph tells why________．

A．Dr． Kell was studying water　　 B．the warm water froze first

C．Dr． Kell used pails in his work　　D．water freezes in underground pipes

5．No water vapor would have escaped into the air if the pails had been_______．

A． warmed B． covered C． shaken D． filled

6．The cold water froze more slowly because_________．

A．salt was added to it　　 B．its pail was smaller

C．there was more of it left D．the air near it was moving

7．When the water was frozen, one of the pails must have had

A．less ice in it than the other　　B．more salt in it than the other

icicles hanging from the rim D．waves on the surface of the ice

答案：C;C;D;B;B;C;A
解析：

提示：

练习册系列答案

相关题目

阅读理解

　　There were smiling children all the way．Clearly they knew at what time the train passed their homes and they made it their business to stand along the railway, were to complete strangers and cheer them up as they rushed towards Penage．Often whole families stood outside their homes and waved and smiled as if those on the trains were their favorite relatives．This is the simple village people of Malaysia．I was moved．

　　I had always traveled to Malaysia by plane or car, so this was the first time I was on a train．I did not particularlf relish the long train joumey and had brought along a dozen magazines to read and reread．I looked about the train．There was not one familiar I sighed and sat down to read my Economics

　　It was not long before the train was across the Causeway and in Malaysia．Johore Baru was just another city like Singapore, so I was tired of looking at the crowds of people as they hurried past．As we went beyond the city, I watched the straight rows of rubber trees and miles and miles of green．Then the first village came into sight．Immediately I came alive, I decided to wave back．

　　From then on my joumey became imeresting．I threw my magazine into the waste basket and decided to join in Malaysian life．Then everything came alive．The mountains seemed to speak to me．Even the trees were smiling．I stared t everything as if I was looking at it for the first time．

　　The day passed fast and I even forgot to have my lunch until I felt hungry．I looked at my wat ch and was surprised that it was 3∶00 p. m．Soon the train pulled up at Butterworth I looked at the people all around me．They all looked beautiful．When my uncle arrive with, I threw my around him to give him a warm hug．I had never done this before．He seemed surprised and then his weather-beaten face warmed up with a huge smile．We walked arm in arm to his car．

　　I looked forward to the return journey．

(1)

The author expected the train trip to be ________．
[　　]
A．	adventurous
B．	pleasnt
C．	exciting
D．	dull

(2)

What did the author remember most fondly of her train trip?
[　　]
A．	The friendly country people．
B．	The mountains along the way．
C．	The crowds of people in the streets．
D．	The simple lunch served on the train．

(3)

Which of the following words can best take the place of the word“relish”in the second paragraph?
[　　]
A．	choose
B．	enjoy
C．	prepare for
D．	carry on

(4)

Where was the writer going?
[　　]
A．	Johore Baru．
B．	The Causeway．
C．	Bunerworth．
D．	Singapore．

(5)

What can we learn from the story?
[　　]
A．	Comfort in traveling by train．
B．	Pleasure of living in the country．
C．	Reading gives people delight．
D．	Smiles brighten people up．

试题分类