请你用化学用语（化学符号）填空： （1）温度计中填充的液态金属是______ ；
题型：填空题
问题：
请你用化学用语（化学符号）填空：
（1）温度计中填充的液态金属是 ______ ；
（2）保持水的化学性质的最小粒子是 ______ ；
（3）m个亚铁离子 ______ ；
（4）地壳中含量最多的非金属元素和金属元素形成的化合物 ______ ．
题型：填空题
阅读理解
One-room schools are part of the United States, and the mention of them makes people feel a
vague longing for "the way things were".
One－room schools are an endangered species, however.For
more than a hundred years one－room schools have been systematically shut down and their students
sent away to centralized schools.As recently as 1930 there were 149,000 one－room schools in the
United States.By 1970, there were 1,800.Today, of the nearly 800 remaining one－room schools,
more than 350 are in Nebraska.The rest are scattered through a few other states that have on their
road maps wide－spaces between towns.
Now that there are hardly any left, educators are beginning to think that maybe there is something
yet to be learned from one－room schools, something that served the pioneers that might serve as well
as today.
Progressive educators have come up with progressive－sounding names like "peer－group teaching"
and "multi－age grouping" for educational procedures that occur naturally in the one－room schools.In
one－room
schools, the ch
ildren teach each other because the teacher is busy part of the time teaching
someone else.A fourth grader can work at a fifth－grade level in math and a third－grade level in English without the shame associated with being left back or the pressures of being skipped ahead.A youngster
with a learning disability can find his or her own level without being separated from the other pupils.In
larger urban schools today, this is called "mainstreaming". A few hours in a small school that has only one
classroom and it becomes clear why so many parents feel it one of the advantages of living in Nebraska
that their children have to go to a one－room school.
1. According to the text, many educators today feel that one－room schools________.
A. need to be shut down
B. are the best in Nebraska
C. are still common in America
D. provide good education
2. One－room schools are in danger of disappearing because________.
A. they all exist in only one state
B. they skip too many children ahead
C. there is a trend toward centralization
D. there is no fourth－grade level in them
3. What is mentioned as a major characteristic of the one－room school?
A. Some children have to be left back.
B. Teachers are always busy.
C. Pupils have more subjects to study.
D. Leaning is at different grade levels at a time.
4. What's the author's attitude toward one－room schools?
A. He prises them.
B. He dislikes them.
C. He shows sympathy.
D. He rejects them.
5. The last sentence suggests that parents living in Nebraska________.
A. don't like centralized schools
B. once studied in one－room schools
C. prefer rural life to urban one
D. came from other states of America