相关习题
 0  36242  36250  36256  36260  36266  36268  36272  36278  36280  36286  36292  36296  36298  36302  36308  36310  36316  36320  36322  36326  36328  36332  36334  36336  36337  36338  36340  36341  36342  36344  36346  36350  36352  36356  36358  36362  36368  36370  36376  36380  36382  36386  36392  36398  36400  36406  36410  36412  36418  36422  36428  36436  151629 

科目: 来源: 题型:

Nowadays, many tall buildings have e___________ for people to go up and down.

查看答案和解析>>

科目: 来源: 题型:

After the war, a new g____________ was set up for that country.

查看答案和解析>>

科目: 来源: 题型:

On seeing the man’s _____face, all are _____ to run away, for he’s got a quite ugly face.

A. frightening; frightened         B. frightened; frightened 

C. frightening, frightening        D. frightened; frightening    

查看答案和解析>>

科目: 来源: 题型:

Great Expectations ______ my favorite book, which ______ by Charles Dickens, and ______ as classic

literature nowadays.

A. is; was written; is seen                          B. are; are written; are seen    

C. is; had been written; is seen               D. are; were written; is being seen

查看答案和解析>>

科目: 来源: 题型:

Pip ______ a gentleman and ______ Estella’s love, who is a beautiful girl.

A. is bent to becoming; winning               B. is bent on becoming; win

C. is determined to become; winning           D. is determined to become; win

查看答案和解析>>

科目: 来源: 题型:

Great Expectations ______ my favorite book, which ______ by Charles Dickens, and ______ as classic

literature nowadays.

A. is; was written; is seen                          B. are; are written; are seen    

C. is; had been written; is seen               D. are; were written; is being seen

查看答案和解析>>

科目: 来源: 题型:

Anyone, if he _______ in his career, must be self- confident and make constant efforts towards his goal.

A. succeeds                   B. will succeed              C. is to succeed         D. is about to succeed

查看答案和解析>>

科目: 来源: 题型:

Coco Cola, in which much sugar         ,is not part of a            diet.

A. contained; health                       B. is found; healthy

C. finding, well                                 D. containing; nutritious

查看答案和解析>>

科目: 来源: 题型:

Mr. Blake ____ Shanghai in a few days. Do you know when the earliest plane ____ on Sunday?

A. is leaving, takes off                 B. leaves, takes off

C. is leaving, is taking off           D. leaves, is taking off

查看答案和解析>>

科目: 来源: 题型:阅读理解

Directions: Read the following text and choose the most suitable heading from A-F for each paragraph. There is one extra heading which you do not need.

Control of Respiration

Basic tips for preserving cut flowers

Role of Respiration

Most Important Aspect of Flower Care

Need for Clean Water

Ways of Stopping Respiration

76. __________

While everybody enjoys fresh cut flowers around his house, few people know how to keep them for as long as possible. This may be done by keeping in mind a few simple facts. The key to keeping fresh cut flowers for a week or more without floral preservatives(which contain biocides that kill bacteria and fungus) is to keep the water fresh and the stems free of air pockets so they can continue to draw up water.

77. __________

An important thing to remember about cut flowers is that they are sensitive to temperature. For example, studies have shown that cut carnations(康乃馨) retain their freshness eight times longer when kept at 12℃ than when kept at 26℃. Keeping freshly harvested flowers at the right temperatures is probably the most important aspect of flower care.

78. __________

Flowers are not intended by nature to live very long. Their biological purpose is simply to attract birds or insects, such as bees, for pollination (授粉). After that, they quickly dry up and die. The process by which flowers consume oxygen and produce carbon dioxide, called respiration (呼吸), generates the energy the flower needs to give the flower its shape and colour. The making of seeds also depends on this energy. While all living things respire, flowers have a high level of respiration. A result of all this respiration is heat, and for flowers the level of heat relative to the mass of the flower is very high. Respiration also brings about the eventual death of the flower. Thus the greater the level of respiration, the sooner the flower dies.

79. __________

How, then, to control the rate at which flowers die? By controlling respiration. How is respiration controlled? By controlling temperature. We know that respiration produces heat, but the reverse is also true. Thus by maintaining low temperatures, respiration is reduced and the cut flower will age more slowly.

80. __________

Another vital factor in keeping cut flowers is the quality of the water in which they are placed. Flowers find it difficult to “drink” water that is dirty or otherwise polluted. Even when water looks and smells clean, it almost certainly contains harmful substances that can endanger the flowers. To rid the water of these unwanted substances, household chlorine bleach (含氯漂白剂) can be used in small quantities. It is recommended that 15 drops of chlorine bleach(at 4% solution) be added to each litre of water. The water and solution should also be replaced each day.

查看答案和解析>>

同步练习册答案