Passage 4
Questions 16 to 20 are based on the following passage．
A number of different aspects of life can influence mental health．In a mid-1970s study of people living in the United States，researchers identified critical areas that influence one’s mental health．These areas are working life，family life，and the social role that one occupies in the community．Negative experiences in these areas，such as an unreasonable boss or a turbulent family life，can reduce one’s overall sense of well-being．
Another important influence on mental health is stress．In general，people experience stress when the demands placed on them exceed the resources they have available to meet those demands．Significant sources of stress include major life events，such as divorce，death of a spouse，loss of a job，and illness in the family．These events can overwhelm a person’s ability to cope and function effectively. In addition，one source of stress may lead to another, as when financial hardship follows job loss．People who experience unusually traumatic events，such as rape and natural disasters，may develop post-traumatic stress disorder．
People may experience chronic stress when confronted with a continuing set of demands that reduce their ability to function．Examples of such demands include working long hours under difficult circumstances and caring for a chronically ill relative．Economic hardship，unemployment，and poverty can also produce chronic stress and undermine mental health．
Some studies suggest that genetic factors may partly determine one’s level of happiness and mental health．People seem to display a characteristic level of well-being，with some people usually feeling happy and others typically feeling sad or unhappy．Researchers have found that although people’s moods change in response to both positive and negative events，the effect wears off over time．For example，people who win the lottery or receive an unexpected promotion may feel happier at first，but over time they return to their former characteristic level of mental health．Research suggests that one’s genetic background—that is，the genes inherited from one’s parents—explains more than half of the differences in people’s characteristic mood levels．Genes may also partly determine the range of ups and downs that people feel，including whether people have large mood swings or remain stable from day to day．
16．According to the passage，the major factors that may reduce one’s sense of psychological well-being include all the following EXCEPT ______·
A．unstable marriage B．genetic heritage
C．bad-tempered managers D．lower social status
17．People experience stress when ______．
A．they have no accessible financial resources
B．they have no social resources at their disposal
C．they feel it hard to shirk family responsibility
D．they have to go beyond their ability to get a job done
18．Chronic stress may result from ______．
A．death of a spouse B．lottery purchases
C．long-time hard work D．failure to be promoted
19．From the last paragraph，it can be inferred that ______.
A．people’s moods are sometimes unstable
B．people cannot escape from negative events
C．Success may produce a long-term effect on people’s mental health
D．parents are partly responsible for their children’s distinctive moods
20．According to the passage，people’s characteristic mood levels may be affected ______．
A．physically B．biologically
C．gradually D．abruptly
