单项式3a2b5的系数是______．

警督是高级警官。( )

下面各句中加点的成语使用错误的一项是（B）

A．我感受铿锵的节奏，婉转悠扬的韵律，领略言外不尽的神韵，更陶醉于诗人们对大自然叹为观止的描画。

B．轰隆的巨响，振聋发聩，游人打着手势在夸张地交谈，却好像失去了声音。

C．富丽堂皇的建筑群，贵族老爷们养尊处优的生活场所已消失得无影无踪了，唯独留下一座简朴的小屋。

D．如果某个民族没有自己的传统文化和文化传统，每一天都是在从头开始去练习生存本领，那情景是不堪设想的。

口腔健康促进的基础是（）

A.一级预防

B.二级预防

C.三级预防

D.社区预防

E.高危及易感人群的特殊防护

阅读理解。

     Learning disabilities are disorders in the ways people understand or use language. They can affect the

ability to listen or think, or to speak, or to read, or to write and do mathematics.

     A person with a learning disability has unusual difficulty in developing these skills. Researchers believe

that learning disabilities are caused by differences in the way that the brain works with information. They

say children with learning disabilities are not unintelligent or do not want to work. Their brains just process

information differently than other people. Researchers say that one in five people in America has some kinds

of learning disability. Almost three million children in America receive some kinds of help in school for a

learning disability.

     How can you tell if someone has a learning disability? Experts look for a difference between how well

a child does in school and the level of intelligence or ability of the child. But there is no sign of a disorder.

A few signs of a learning disability include not connecting letters with their sounds or not understanding

what is read. A person with a learning disability may not be able to understand a funny story. They may

not follow directions. They may not read numbers correctly or know how to start a task Different people

have different kinds of learning disabilities. Another may have difficulty understanding what people are

saying. Still another may not be able to express ideas in writing.

     These different kinds of learning disabilities are known by different names. For example, a person who

has difficulty reading may have dyslexia. Someone who cannot do mathematics may have a disorder called

dyscalculia (计算困难).

     Experts say learning disabilities cannot be cured. But people who have them can be helped. Teachers

and parents can help young people with learning disabilities to learn successfully.

1. What does the passage mainly talk about?

A. Some kinds of help in school for a learning disability.

B. How to cure learning disabilities.

C. Causes of learning disabilities.

D. Learning disabilities.

2. It is believed that ____ is the main cause of learning disabilities.

A. different brain

B. unintelligence

C. not wanting to work

D. the way the brain works with information

3. People with learning disabilities may have no trouble ____.

A. understanding a funny story

B. following directions

C. dressing themselves

D. reading numbers correctly  

4. The underlined word in the 4th paragraph probably means ____.

A. difficulty in seeing

B. problem in reading

C. trouble in listening

D. brain disorder

有的树木在生长季节内，因菌害、虫害、霜雹、火灾、干旱等影响，同一生长周期内会形成两个或两个以上的生长轮。