Reading comprehension -TOEFL- Lesson 30
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.

1. What does the passage mainly discuss?
(A) risk factors in heart attacks
(B) seasonal and temporal patterns of heart attacks
(C) cardiology in the 1980s
(D) diet and stress as factors in heart attacks
2. In line 2, the word "potential" could best be re-placed by which of the following?
(A) harmful
(B) primary
(C) unknown
(D) possible
3. The word "trigger" as used in line 3 is closest in meaning to which of the following?
(A) involve
(B) affect
(C) cause
(D) encounter
4. Which of the following could best replace the word "incidence" as used in line 4?
(A) increase
(B) rate
(C) chance
(D) factor
5. The author uses the word "temporal" in line 6 to mean
(A) affected by
(B) of a certain date
(C) expected
(D) regularly
6. The phrase "susceptible to" in line 9 could best be replaced by
(A) aware of
(B) affected by
(C) accustomed
(D) prone to
7. According to the passage, which of the following is NOT a possible cause of many heart attacks?
(A) decreased blood flow to the heart
(B) increased blood pressure
(C) lower heart rate
(D) increase in hormones
8. The word "phenomenon" in line 10 refers to which of the following?
(A) habit
(B) illness
(C) occurrence
(D) activity
9. The word "implicated" in line 15 could best be replaced by which of the following?
(A) indicated
(B) disregarded
(C) investigated
(D) discovered
10. Which of the following is NOT cited as a possible risk factor?
(A) having a birthday
(B) getting married
(C) eating fatty foods
(D) being under stress
11. Which of the following does the passage infer?
(A) We now fully understand how risk factors trigger heart attacks.
(B) We recently began to study how risk factors trigger heart attacks.
(C) We have not identified many risk factors associated with heart attacks.
(D) We do not fully understand how risk factors trigger heart attacks.
12. As used in line 16, which of the following could best replace the word "reveal"?
(A) show
(B) observe
(C) mean
(D) explain