Read the following passage carefully and then choose the best answer to  each question. 
 
As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.
   Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.
   In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered.
Which of the following does the passage infer?
A.We have not identified many risk factors associated with heart attacks.
B.We now fully understand how risk factors trigger heart attacks.
C. We do not fully understand how risk factors trigger heart attacks
D.We recently began to study how risk factors trigger heart attacks.

Các câu hỏi liên quan

Read the following passage carefully and then choose the best answer to  each question. 
 
In most discussions of cultural diversity, attention has focused on visible, explicit aspects of culture, such as language, dress, food, religion, music, and social rituals. Although they are important, these visible expressions of culture, which are taught deliberately and learned consciously, are only the tip of the iceberg of culture. Much of culture is taught and learned implicitly, or outside awareness. Thus, neither cultural insiders nor cultural outsiders are aware that certain “invisible” aspects of their culture exist.
Invisible elements of culture are important to us. For example, how long we can be late before being impolite, what topics we should avoid in a conversation, how we show interest or attention through listening behavior, what we consider beautiful or ugly- these are all aspects of culture that we learn and use without being aware of it. When we meet other people whose invisible cultural assumptions differ from those we have learned implicitly, we usually do not recognize their behaviour as cultural in origin.
Differences in invisible culture can cause problems in cross-cultural relations. Conflicts may arise when we are unable to recognize others’ behavioral differences as cultural rather than personal. We tend to misinterpret other people’s behaviour, blame them, or judge their intentions or competence without realizing that we are experiencing cultural rather than individual differences.
Formal organizations and institutions, such as schools, hospitals, workplaces, governments, and the legal system are collection sites for invisible cultural differences. If the differences were more visible, we might have less misunderstanding. For example, if we met a man in a courthouse who was wearing exotic clothes, speaking a language other than ours, and carrying food that looked strange, we would not assume that we understood his thoughts and feelings or that he understood ours. Yet when such a man is dressed similarly to us, speaks our language, and does not differ from us in other obvious ways, we may fail to recognize the invisible cultural differences between us. As a result, mutual misunderstanding may arise
The word “exotic” in paragraph 4 could best be replaced by__________.
A.foreign                                                                 
B.informal
C.formal
D.expensive

Read the following passage carefully and then choose the best answer to  each question. 
 
In most discussions of cultural diversity, attention has focused on visible, explicit aspects of culture, such as language, dress, food, religion, music, and social rituals. Although they are important, these visible expressions of culture, which are taught deliberately and learned consciously, are only the tip of the iceberg of culture. Much of culture is taught and learned implicitly, or outside awareness. Thus, neither cultural insiders nor cultural outsiders are aware that certain “invisible” aspects of their culture exist.
Invisible elements of culture are important to us. For example, how long we can be late before being impolite, what topics we should avoid in a conversation, how we show interest or attention through listening behavior, what we consider beautiful or ugly- these are all aspects of culture that we learn and use without being aware of it. When we meet other people whose invisible cultural assumptions differ from those we have learned implicitly, we usually do not recognize their behaviour as cultural in origin.
Differences in invisible culture can cause problems in cross-cultural relations. Conflicts may arise when we are unable to recognize others’ behavioral differences as cultural rather than personal. We tend to misinterpret other people’s behaviour, blame them, or judge their intentions or competence without realizing that we are experiencing cultural rather than individual differences.
Formal organizations and institutions, such as schools, hospitals, workplaces, governments, and the legal system are collection sites for invisible cultural differences. If the differences were more visible, we might have less misunderstanding. For example, if we met a man in a courthouse who was wearing exotic clothes, speaking a language other than ours, and carrying food that looked strange, we would not assume that we understood his thoughts and feelings or that he understood ours. Yet when such a man is dressed similarly to us, speaks our language, and does not differ from us in other obvious ways, we may fail to recognize the invisible cultural differences between us. As a result, mutual misunderstanding may arise
The following sentence can be added to paragraph 2 of the passage.
Rather, we see them as rude or uncooperative, and we may apply labels to them, such as “passive aggressive.”
Where would it best fit in the paragraph? Choose A, B, C or D
A.……Invisible elements of culture are important to us.
B.…….. When we meet other people whose invisible cultural assumptions differ from those we have learned implicitly, we usually do not recognize their behaviour as cultural in origin.
C.………….
D.…… For example, how long we can be late before being impolite, what topics we should avoid in a conversation, how we show interest or attention through listening behaviour, what we consider beautiful or ugly- these are all aspects of culture that we learn and use without being aware of it.