Since there are so many English expressions that exist, most Korean students confuse what to use when they choose one expression among some expressions that have similar meaning. One of the most often used words when they both speak and write is should and must. Many students use these words when they try to convey duty or obligation. To find out the differences in meaning and usage of should and must, I examined 100 KWIC concordance lines and compared both words from The Corpus of Contemporary American English (Davies, 2008-). Some interesting significance could be found through the process of examining two words by The Corpus program.
First of all, when people speak, should is mostly used with “be”, which means it is usually used as passive forms. According to the list of the words usually come after should, top three words are “pointed,” “banned,” and “ashamed.” “It should be pointed (out)” and “smoking should be banned” are some examples of usage of should in passive sentences. Contrary to the way most Korean students use should, object, not subject, is usually placed before should.
In addition, must is used when people describes their feelings in a spoken setting. Because most Korean students use must as imperative sentences, this finding would be remarkably interesting, especially to Korean students. For example, the way students usually use must is “You must go right now;” however, the way must is used in The Corpus is “it must be very frustrating for you.” The words that usually occur with must are “awfully” and “frustrating.” In other words, it was found out that must is usually used as describing feeling rather than imperative sentences.
Furthermore, it was also found that should and must are differently used when people write. According to The Corpus, should is often used with “maybe” or “probably.” “You probably shouldn’t be a smoker” and “maybe you should do what I do.” are some examples of should in newspapers. When it is considered, people use should when they are less certain about something. On the other hand, people use must when they order something to someone in a more emphatic tone. The words usually come after must are “obey,” “begin,” and “pay.”
The corpus study indicated several differences in usage between should and must in both spoken and written settings. To learn these confusing expressions and words will surely help Korean students speak and write in English more naturally.
Reference:
Davies, Mark. (2008-) The Corpus of Contemporary American English: 450 million words, 1990-present. Available online at http://corpus.byu.edu/coca/.