已知|a|=3,|b|=4,(a+b)•(a+3b)=33,则a与b的夹角为__

题型:填空题

问题:

已知|
a
|=3,|
b
|=4,(
a
+
b
)•(
a
+3
b
)=33,则
a
b
的夹角为______.
考点:用数量积表示两个向量的夹角
题型:填空题

Minister Bill De Blasio     in office fewer than 48 hours when he came face to face with his biggest challenge in his life.

A.has been

B.had been

C.would be

D.is

题型:填空题

下列说法中不正确的是[ ]

A.穿衣镜成正立等大的虚像

B.照相机成倒立缩小的实像

C.汽车观后镜成正立缩小实像

D.幻灯机成倒立放大实像

题型:填空题

俗话说“食不言,寝不语”.其实,吃饭时不能大声谈笑是有科学道理的,原因是(  )

A.流经消化器官的血流量减少

B.唾液腺分泌唾液的量较少

C.食物容易由咽误入气管

D.有利于保护声带

题型:填空题

阅读理解。

     The time of year a baby is born can shape what profession they will embark on(从事) in later life,

a new study has suggested.

     Being born in a certain month appears to indicate the statistical likelihood of what job a person wil

l end up with, the study by the Office for National Statistics found.

     Researchers have uncovered that the month in which babies are born could also affect everything

from intelligence to length of life.

     A child born December is more likely to become a dentist while someone whose birthday falls in

January will tend to a debt collector, they found. A February birth appears to increase the chances

of being an artist while March babies appear to go on to become pilots. Meanwhile, April and May

are said to have a fairly even spread of professions, births in the summer months mean a much lower

chance of becoming a high-earning football player, doctor or dentist.

    The study was got by researchers who analyzed the birth months of people in 19 separate occupations

using information from the last survey, the Daily Mail reported. Although these trends may be difficult

to explain, correlations between birth months and specific health problems have a scientific basis.

     Spring babies are at greater risk of illnesses including schizophrenia, Alzheimer's disease, asthma

and autism.

     They may also be less clever than classmates born in other parts of the year.

1. From the passage we can know if a baby is born on February. 20, it will probably become a _____.

A. footballer      

B. doctor        

C. pianist      

D. teacher

2. According to the passage, which of the following statements is true?

A. Researchers can explain why babies will have different careers in the future

B. Researchers make the conclusion just by analyzing the birth of people in 19 separate occupations

C. Being born in a certain month will certainly determine what a baby will do in the future

D. Being born in different months has no influence on what a baby will do in the future

3. What does the underlined word "correlation" in Paragraph 5 mean?

A. close connection            

B. great influence  

C. effective solution             

D. reasonable conclusion  

4. What's the purpose of this passage?

A. To discuss a baby's birth month      

B. To describe different professions

C. to explain babies' some trends      

D. To introduce a new discovery

题型:填空题

ASTm升高提示的临床疾病是()

A.肝硬变

B.慢性肝炎

C.重症肝炎、肝坏死

D.肝癌

E.阻塞性黄疸

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