Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct word or phrase for each of blanks. Fill in the appropriate word in question 48

When you read something in a foreign language, you frequently come across words you do not (45)______ understand. Sometimes you (46)______ the meaning in a dictionary and sometimes you guess. The strategy you adopt depends very much upon the (47)______of accuracy you require and the time at your disposal. If you are the sort of person who tends to turn to the dictionary frequently, it is (48)_______remembering that every dictionary has its limitations. Each definition is only an approximation and one builds up an accurate picture of the meaning of a word only after meeting it in a (49)__________of contexts. It is also important to recognize the special dangers of dictionaries that translate from English into your native language and vice versa. If you must use a dictionary, it is usually far safer to (50)________an English- English dictionary. In most exams you are not permitted to use a dictionary. (51)__________you are allowed to use one, it is very time- consuming to look up words, and time in exams is usually limited. You are, (52)______, forced to guess the meaning of unfamiliar words. When you come across unknown words in an exam text, it is very easy to panic. However, if you develop efficient techniques for guessing the meaning, you will(53)__________a number of possible problems and help yourself to understand far more of the text than you at first likely. Two strategies which may help you guess the meaning of a word are: using contextual clues, both within the sentence and outside, and making uses (54)_____ clues derived from the formation of the word.

A. valuable

B. worth

C. vital

D. essential