For many people today, reading is no longer relaxation. To keep up their work they must read letters, reports, trade publications, interoffice communications, not to mention newspapers and magazines: a never-ending flood of words. In 　1　a job or advancing in one, the ability to read and comprehend 　2　can mean the difference between success and failure. Yet the unfortunate fact is that most of us are 　3　readers. Most of us develop poor reading 　4　at an early age, and never get over them. The main deficiency 　5　in the actual stuff of language itself－words. Taken individually, words have 　6　meaning until they are strung together into phrases, sentences and paragraphs. 　7　,however, the untrained reader does not read groups of words. He laboriously reads one word at a time, often regressing to 　8　words or passages. Regression, the tendency to look back over 　9　you have just read, is a common bad habit in reading. Another habit which 　10　down the speed of reading is vocalization—sounding each word either orally or mentally as 　11　reads.
　　To overcome these bad habits, some reading clinics use a device called an 　12　, which moves a bar (or curtain) down the page at a predetermined speed. The bar is set at a slightly faster rate 　13　the reader finds comfortable, in order to “stretch” him. The accelerator forces the reader to read fast, 　14　word-by-word reading, regression and sub vocalization, practically impossible. At first 　15　is sacrificed for speed. But when you learn to read ideas and concepts, you will not only read faster 　16　your comprehension will improve. Many people have found 　17　reading skill drastically improved after some training. 　18　Charlie Au, a business manager, for instance, his reading rate was a reasonably good 172 words a minute 　19　the training, now it is an excellent 1,378 words a minute. He is delighted that how he can 　20　a lot more reading material in a short period of time.
______

A.what

B.which

C.that

D.if