以下标1表示流域入流，下标2表示流域出流，则闭合流域（） A.R1＝0 B.R2＝0
题型：单项选择题
问题：
以下标1表示流域入流，下标2表示流域出流，则闭合流域（）
A.R1＝0
B.R2＝0
C.R1＝0和R2＝0
D.R1＝0和E＝0
题型：单项选择题
发展性试题。
请认真阅读下列短文，并根据所读内容在文章后表格中的空格里填入最恰当的单词。
注意：每空格1个单词。
Most people feel lonely sometimes, but it usually only lasts between a few minutes and a few hours. This
kind of loneliness is not serious. In fact, it is quite normal. For some people, though, loneliness can last for
years, Now researchers say there are three different types of loneliness.
The first kind of loneliness is temporary. This is the most common type. It usually disappears quickly and
does not require any special attention, The second kind, situation-for example, family problem, the death of a
loved one, or moving to a new place. Although this kind of loneliness can cause physical problems. such as
headaches and sleeplessness, it usually does not last for more than a year.
The third kind of loneliness is the most severe. Unlike the second type, chronic (the opposite of
"temporary") usually lasts more than two years and has no specific cause. People who experience habitual
loneliness have problems socializing and becoming close to others. Unfortunately, many chronically lonely
people think there is little or nothing they can do to improve their condition.
Psychologists agree that one important factor in loneliness is a person's social contacts, for example,
friends, family members. co-workers, etc. we depend on various people for different reasons; For instance, our
families give us emotional support, our parents and teachers give us guidance, and our friends share similar
interests and activities. However, psychologists have found that, though lonely people may have many social
contacts, they sometimes feel they should have more, They question their popularity.
Psychologists are trying to find ways to help habitually lonely people for two reasons: they are unhappy and
unable to socialize and there is a connection between chronic loneliness and serious illness as heart disease,
while temporary and situational loneliness can be a sad, and sometimes dangerous condition.
Loneliness and Disease
