第一节 完形填空(共10小题；每小题2分，满分20分)
阅读下面短文，掌握其大意，然后从21~30各题所给的A、B、C和D项中，选出最佳选项，并在答题卡上将该项涂黑。
The latest reform in testing is the computerized test. Test questions and answer choices are presented on the  21  and students can answer with a tap of the keyboard or a click of the mouse. Before the actual test begins, there usually is an instruction showing how to use the computer to  22  the questions. Scores are displayed on the screen at the end of the test so that a student has immediate feedback  23  having to return several days later for results.
Some computerized tests are “adaptive”. This means that a test question is selected from a large pool of items based on how the test taker has responded to the  24  questions. The first question presented is of medium difficulty. If the test taker answers  25  , the next item will be more difficult. If he or she answers incorrectly, the next question will be easier. The computer  26  questions by level of difficulty and many other factors such as sex, race and age references, subject area the question is drawn from, and form of question, before presenting it on the screen. In this way, the questions are “adapted” to find the true skill  27  of the test taker.
Among all the conveniences of computerized testing, there are some  28  . No longer can you have a quick look at the  29  test, answer the easy questions first, and come back later to finish the difficult ones. Test items are presented one at a time, and you must choose an answer in order to move on to the next question. Once you have confirmed your answer, you cannot go back to  30  it if，later on, you realize that your answer was wrong．
21．A．screen     B．paper       C．board       D．surface
22．A．put aside   B．concentrate on    C．respond to   D．apply to
23．A．other than  B．rather than   C．regardless    D．as to
24．A．previous   B．basic       C．following     D．single
25．A．briefly     B．smartly     C．correctly     D．thoughtfully
26．A．classifies   B．answers     C．considers    D．recognizes
27．A．standard    B．factor      C．pattern       D．level
28．A．qualities    B．limits      C．services      D．features
29．A．formal     B．objective    C．final        D．entire
30．A．identify    B．exchange    C．change      D．overlook