As a product of modern educational technology, PED provides great convenience to English learners. It is becoming more and more popular among users for its incomparable advantages. However, because of the limitations of technology, there are also some undeniable disadvantages. 2.3.1 The advantages of PED The most remarkable advantage of PED is its quick retrieval and high efficiency. Users can obtain the needed information about words in a blink of eyes. Compared with the traditional paper dictionary, PED can save a lot of time and effort. Owing to its small size and light weight, PED can be carried from one place to another and can be used at any time and in any place. Additionally, PED is usually based on the traditional paper dictionary which has a solid foundation of lexicography. Due to the large capacity, new vocabulary can be introduced into PED quickly. Theoretically speaking, it has an unlimited and infinite capacity 140. Moreover, PED provides lots of auxiliary functions. Many PEDs have download function and can be upgraded regularly. Users could amuse themselves by listening to music or playing games when they are tired. To sum up, there are superior advantages of PED with which the paper dictionary could not compare. It offers information, convenience, efficiency as well as entertainment. 2.3.2 The disadvantages of PED Though PED provides great convenience to English learners, its negative effects have also become more and more visible. Most PED makers are not professionals but computer technicians without lexicographical knowledge. Some dictionaries declare that they cover hundreds of thousands of vocabularies, but actually they are the total sum of the several paper dictionaries that the PED contains. Many words, phrases and idioms overlap. Besides, the vocabulary information some PEDs provide is too limited. For example, some PEDs only give brief explanation of word meaning without examples; sometimes senses for headwords are ordered in an unscientific way. Furthermore, there are too many functions unrelated to language learning which may hinder rather than help. In addition, because of the small screen, PED can only show three to four lines of information one time. To find the necessary information, users have to downpage several times. Consequently, it may be a waste of time to use PED, especially when polysemic words are consulted. More importantly, frequent use of PED may breed over-dependence on dictionary. Students tend to overuse PEDs, therefore they would refer to it whenever they come across a new word without employing other strategies of vocabulary learning like contextual guessing. In brief, PED has its limitations and drawbacks, which might exert negative influence on users 138-139. 3. The current use of PED among college students It is a undeniable fact that PED has gained great popularity among college and university students. An investigation on 251 non-English majors of Shanghai University shows that the ED owners are about 173, among which 134 students have PED. Namely, 57% students possess PED. While meeting new words in learning, 58% students would choose PED. 62% use PED when they meet words that they do not know how to pronounce. While reading or having classes, students use PED most frequently 174-175. The writer of this paper has also done a survey on the current use of PED among English majors, and found that among 32 students, 19 have PED. 10 students plan to buy one, while 3 students do not intend to. Moreover, a majority, about 73% students regard it as an indispensable tool in English learning. They think that it is convenient, time-saving and labor-saving to look up new words in PED when they are reading, translating or writing. Many investigations show that among all types of dictionaries, PED is also the one used most frequently. Lots of students become over- dependent on PED. When encountering new words, they would refer to it without considering whether it is necessary or not. Yet the words that have been consulted would be forgotten a moment later, so they have to look up them again. Moreover, they are content to learn a little about the new words 179-181. For instance, many students just look at the meaning of a word, ignoring other relevant information about usage, grammar or collocation. So they cannot master a word as a whole. In short, popular as it is, PED also brings about many problems. Therefore, it is of vital importance to probe into the appropriate use of PED. That is what the next session of the paper is going to discuss. 4. The use of PED in English learning As mentioned above, PED has great impact on English learning, so it is necessary and important to learn how to use it appropriately and effectively to facilitate the learning process. A good user should know at least three points as follows: 4.1 How to choose a proper PED 4.1.1 To know about the needs |