델타스 NG 토플(Delta's Toefl Reading Sections)--Referents

델타스 NG 토플(Delta's Toefl Reading Sections)--Referents

 

7. Here are some examples:

 

Some foods require very specific enzymes for digestion. Milk sugar, which is called lactose, needs an enzyme called lactase to convert it to glucose and galactose, carbonhydrates needed by the body for energy. Some people do not produce lactase or have deficient amount of enzyme. Lactase deficiency may be inherited, and in infants it occurs in severe form, persisting throughout life. Some people develop the condition later in life, many when they are in their forties. People of Asian or African heritage develop the condition more frequently. Around 90 percent of the former and 75 percent of the latter have varying severity of lactase deficiency. People with the disorder, also called lactose intolerance, have difficulty digesting cow's milk. The condition currently considered incurable; however, symptoms can be controlled and relieved with a diet free of milk and milk products.(147 words)

 

 

The word it in the passage refers to

 

A. digestion

B. milk sugar

C. the enzyme

D. lactase deficiency

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The referent of it is something that occurs in severe form in infants. The subject of the sentence is Lactase deficiency. Logic tells you that it refers to lactase deficiency, which is the correct answer.

 

You can check the answer by reading the sentence with lactase deficiency in place of it: Lactase deficiency may be inherited, and in infants lactase deficiency occurs in severe form, persisting throughout life.