题目内容
When we see well, we do not think about our eyes very often. (79) It is only when we cannot see perfectly that we realize how important our eyes are. People who are nearsighted can only see things that are very close to their eyes. Everything else seems blurry(模糊的).Many people who do a lot of close work, such as writing, reading and sewing, become nearsighted. Then they have to wear glasses in order to see distant objects clearly. People who are farsighted suffer from just the opposite problem. They can see things that are far away, but they have difficulty in reading a book unless they hold it at arm’s length. If they want to do much reading, they must get glasses, too. Other people do not see clearly because their eyes are not exactly the right shape. They have what is called astigmatism (散光). This, too, can be corrected by glasses. Some people’s eyes become cloudy because of cataracts(白内障). Long ago these people often became blind. Now, however, it is possible to operate on the cataracts and remove them. Having two good eyes is important for judging distances. Each eye sees things from a slightly different angle. To prove this to yourself, look at an object out of one eye; then look at the same object out of your other eye. You will find the object’s relation to the background and other things around it has changed. The difference between these two different eye views helps us to judge how far away an object is. People who have only one eye cannot judge distance as people with two eyes. When things far away seem indistinct, one is probably ______.
查看答案
搜索结果不匹配？点我反馈
更多问题
The biggest safety threat facing airlines today may not be a terrorist with a gun, but the man with the portable computer in business class. In the last 15 years, pilots have reported well over 100 incidents that could have been caused by electromagnetic interference. The source of this interference remains unconfirmed, but increasingly, experts are pointing the blame at portable electronic devices such as portable computers, radio and cassette players and mobile telephones. RTCA, an organization which advises the aviation (航空) industry, has recommended that all airlines ban(禁止)such devices from being used during "critical" stages of flight particularly take- off and landing. Some experts have gone further, calling for a total ban during all flights. (76) Currently, rules on using these devices are left up to individual airlines. And although some airlines prohibit passengers from using such equipment during take- off and landing, most are reluctant to enforce a total ban, given that many passengers want to work during flights. The difficulty is predicting how electromagnetic riel& might affect all aircraft’s computers. (77)Experts know that portable devices emit radiation which affects those wavelengths which aircraft use for navigation and communication. But, because they have not been able to reproduce these effects in a laboratory, they have no way of knowing whether the interference might be dangerous or not. The fact that aircraft may be vulnerable(易受损的)to interference raises the risk that terrorists may use radio systems in order to damage navigation equipment. (78) As worrying, though, is the passenger who can’t hear the instructions to turn off his radio because the music’s too loud. Why is it difficult to predict the possible effects of electromagnetic fields on an airplane’s computers
心理收入是指员工在工作过程中感受到的尊重、友谊、关怀、个人价值及获得的学习机会、发展空间等。企业可以通过改进这几个方面的工作，使员工们更加努力地工作，为企业做出更大的贡献。 根据上述定义，下列不属于心理收入的是( )。
下列加点字的读音全都正确的一组是( )。
The biggest safety threat facing airlines today may not be a terrorist with a gun, but the man with the portable computer in business class. In the last 15 years, pilots have reported well over 100 incidents that could have been caused by electromagnetic interference. The source of this interference remains unconfirmed, but increasingly, experts are pointing the blame at portable electronic devices such as portable computers, radio and cassette players and mobile telephones. RTCA, an organization which advises the aviation (航空) industry, has recommended that all airlines ban(禁止)such devices from being used during "critical" stages of flight particularly take- off and landing. Some experts have gone further, calling for a total ban during all flights. (76) Currently, rules on using these devices are left up to individual airlines. And although some airlines prohibit passengers from using such equipment during take- off and landing, most are reluctant to enforce a total ban, given that many passengers want to work during flights. The difficulty is predicting how electromagnetic riel& might affect all aircraft’s computers. (77)Experts know that portable devices emit radiation which affects those wavelengths which aircraft use for navigation and communication. But, because they have not been able to reproduce these effects in a laboratory, they have no way of knowing whether the interference might be dangerous or not. The fact that aircraft may be vulnerable(易受损的)to interference raises the risk that terrorists may use radio systems in order to damage navigation equipment. (78) As worrying, though, is the passenger who can’t hear the instructions to turn off his radio because the music’s too loud. What is said about the over 100 aircraft incidents in the past 15 years
微信支付 
支付宝支付