A、Ignoring the general meaning of the text. B、Paying little attention to the printing mistakes. C、Pursuing a thorough understand

There is no doubt that adults, and even highly educated adults, vary greatly in the speed and efficiency of their reading. Some proceed very slowly throughout: others dash along too quickly and then have to go back again. Poor readers in particular may lack the ability to vary their manner of reading according to the type of reading matter and their intentions in reading it. A good reader can move at a great speed through the text of a novel or similar light reading matter. In reading more difficult material, with the intention of taking in the whole of it, he will proceed more slowly, but even then he will vary his pace, concentrating on the key words and passages, re-reading them several times or passing more quickly over the remainder. A less efficient reader tends to maintain the same speed whatever the material he reads. Therefore, even light reading matter gives him little pleasure because he reads so slowly. But this pace may be too fast for really difficult material which requires special concentration at difficult points.
    A type of reading which needs careful attention to detail is proofreading. In order to detect misprints in a sample print the reader needn’t notice so much the meaning of what he reads as the exact shape and order of words in the text. This is extremely difficult for most people, since they are used to ignoring such details. In fact, considerable practice is required to practise this task efficiently and it can be done only by reading very slowly, and by paying comparatively little attention to the general meaning of the text.
16. What idea does the speaker mainly want to convey?
17. What is typical of inefficient readers in terms of reading speed?
18. What does proofreading require?