除去下列物质中的少量杂质,所用试剂或方法不正确的是( ) 选项物质杂质试剂或方法

题型:选择题

问题:

除去下列物质中的少量杂质,所用试剂或方法不正确的是(  )

选项物质杂质试剂或方法
ANaCl 固体泥沙加水溶解、过滤、蒸发
BNaCl 溶液Na2C03    滴加硫酸溶液至不再产生气泡
CKNO3溶液    Ba(N032  滴加适量K2SO4溶液、过滤
DN202通过红热的铜丝

A.A

B.B

C.C

D.D

考点:过滤盐的性质物质的除杂
题型:选择题

阅读理解, 根据短文内容,选择最佳选项.

    The nine-year-old Marc Yu is called Little Mozart. He is too short to reach the pedals  (踏板) of a

piano. Marc, from California, USA, says, "The problem is that my legs aren't straight enough, so I have

to get very close to the piano."

    Marc's 34-year-old mother played Beethoven's CDs to him when she was pregnant (怀孕的). Marc

started playing the piano at a birthday party when he was only two. While the other children were  singing "Twinkle, twinkle, little star …", he walked over to the piano and started playing the song. It  astonished

his mother, because that was the first time he'd been near a piano. Marc gave his first public performance,

playing Beethoven, at six, the same age as Mozart. After that concert, Marc won a £225,000 university

scholarship (奖学金).

    At present he practices the piano eight hours a day. He also studies  part-time at the famous  Colbum

Music School  in Los Angeles, and  flies once a month to China for lessons at Shanghai Music School.

Marc  says, "I like  playing  the piano  because it makes me have a  lot of different  feelings - sadness,

excitement, happiness and so on. I like playing  difficult pieces,  especially those that my teacher says I

shouldn't."

1. The nine-year-old Marc Yu is from        .

A. China

B. France

C. Canada

D. the United States

2. Marc played the piano at the age of        for the first time.

A. two        

B. five        

C. six          

D. nine

3. According to the passage, the underlined word "astonished" means "     " in Chinese.

A. 使……理解

B. 使……担心

C. 使……惊奇

D. 使……难过

4. At present Marc practices playing the piano        .

A. once a month

B. eight hours a day

C. in his free time            

D. only on weekends

5. What Marc says in the last paragraph tells us that       .

A. he likes challenges

B. he doesn't like challenges

C. he is afraid of challenges

D. he wants to give up music

题型:选择题

下列句子中没有语病的一项是

A.新加坡的竹节虫不仅体色几乎和竹子一样,体形在安静时完全像一根树枝。

B.这次学术会,收获很大,时间并不长。

C.鸟的翅膀不管多么完美,如果不凭借空气,鸟就永远不能飞到高空。

D.大气中臭氧层的减薄及南极上空臭氧洞的不断扩大是由于人类大量放氯氟碳类物质造成的,这不是天灾而是人祸。

题型:选择题

当多人绑挂同一负载时,起吊前,()。

A、司机应确认绑挂的质量;

B、应增加指挥人数;

C、应作好呼唤应答;

D、应确认绑挂人员已全部离开

题型:选择题

男性,69岁,因头痛、头晕、右半身麻木无力2个月入院。4年前发现血压高,服药可降至正常。体检:神清,血压正常,眼底视 * * 边缘模糊不清。右面部感觉减退,双眼外展神经轻度麻痹,右口角力弱,右侧肢体不全瘫,右侧病理反射阳性。胸片右肺第2肋间可见阴影。

为明确诊断,最优先安排的检查是()

A.脑血管造影

B.头部CT或MRI

C.脑超声波

D.腰穿

E.胸部CT

题型:选择题

对于同频切换场景,以下哪一个参数对于切换影响不大()。

A.Ofn

B.Ocn

C.Ocs

D.Hys

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