[单项选择]Now let us look at how we read. When we read a printed text, our eyes move across a page in short, jerky movement. We recognize words usually when our eyes are still when they fixate. Each time they fixate, we see a group of words. This is known as the recognition span or the visual span. The length of time for which the eyes stop—the duration of the fixation—varies considerably from person to person. It also varies within any one person according to his purpose in reading and his familiarity with the text. Furthermore, it can he affected by such factors as lighting and tiredness.
Unfortunately, in the past, many reading improvement courses have concentrated too much on how our eyes move across the printed page. As a result of this misleading emphasis on the purely visual aspects of reading, numerous exercises have been devised to train the eyes to see more words at one fixation. For instance, in some exercises, words are flashed on to a screenfor, say, atenthor a twentieth of a s
A. one’s familiarity with the text
B. one’s purpose in reading
C. the length of a group of words
D. lighting and tiredness

[单项选择]Now let us look at how we read. When we read a printed text, our eyes move across a page in short, jerky movement. We recognize words usually when our eyes are still when they fixate. Each time they fixate, we see a group of words. This is known as the recognition span or the visual span. The length of time for which the eyes stop—the duration of the fixation—varies considerably from person to person. It also varies within any one person according to his purpose in reading and his familiarity with the text. Furthermore, it can he affected by such factors as lighting and tiredness.
Unfortunately, in the past, many reading improvement courses have concentrated too much on how our eyes move across the printed page. As a result of this misleading emphasis on the purely visual aspects of reading, numerous exercises have been devised to train the eyes to see more words at one fixation. For instance, in some exercises, words are flashed on to a screenfor, say, atenthor a twentieth of a s
A. requires a reader to take in more words at each fixation
B. requires a reader to see words more quickly
C. demands an deeply-participating mind
D. demands more mind than eyes

[单项选择]Let us now see how randomization is done when a collision occurs. After a ______, time is divided into discrete slots whose length is equal to the worst-case round-trip propagation time on the ether (2t). To accommodate the longest path allowed by Ethernet, the slot tome has been set t0 512 bit times, or 51.2μsec.A.datagram B.collision C.connection D.service

[填空题]Let us see how dictionaries are made and how editors arrive at definitions. The task of writing a dictionary begins with the reading of vast amounts of the (47) of the period or the subject that the dictionary is to cover. As editors read, they copy on cards every interesting or rare word, every unusual or (48) occurrence of a common word, a large number of common words in their ordinary uses, and also the sentences in which each of these words appears, thus:
pail
The daily pails bring home increase of milk.
Keats, Endymion
The (49) of each word is collected, along with the word itself. For a really big job of dictionary writing, such as the Oxford English Dictionary, millions of such cards are collected, and the task of editing (50) decades. As the cards are collected, they are alphabetized and (51) When