下列关于实验现象的描述正确的是 A．红磷在空气中燃烧，冒出浓厚的白雾 B．铁丝在

发布时间：2017-05-19 23:15 │ 来源：www.tikuol.com

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问题：

下列关于实验现象的描述正确的是

A．红磷在空气中燃烧，冒出浓厚的白雾

B．铁丝在空气中燃烧，火星四射，生成浅绿色固体

C．硫粉在氧气中燃烧，发出蓝紫色火焰、放出大量的热

D．向鸡蛋清溶液中加入饱和硫酸铵溶液，无沉淀析出

考点：氧气的制取和收集氧气的用途氧气的工业制法自然界中的氧循环

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完形填空。

I ① a good friend in my ② . It is a bird. ③ name is Polly. ④ three years old. It is yellow and
very ⑤ . I play ⑥ it ⑦ school. My classmates—Ann and Kate often ⑧ and see it. Polly can ⑨ every day. I ⑩ it to sing "A B C". Now it can sing "A B C". I like it very much.

（     ）①A. have
（     ）②A. home
（     ）③A. It's
（     ）④A. Its
（     ）⑤A. beautifully
（     ）⑥A. and
（     ）⑦A. before
（     ）⑧A. come
（     ）⑨A. sang
（     ）⑩A. teaches

B. had
B. basket
B. Its
B. She's
B. beautiful
B. to
B. after
B. go
B. is singing
B. teachers

C. has
C. box
C. His
C. He's
C. tall
C. with
C. behind
C. came
C. to sing
C. taught

D. am
D. schoolbag
D. Her
D. It's
D. short
D. for
D. in front of
D. comes
D. sing
D. teach

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sin200°cos140°-cos160°sin40°=______．

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《煤矿防治水规定》规定，探水钻孔除兼作堵水或者疏水用的钻孔外，终孔孔径一般不得大于（）mm。

A、42

B、56

C、75

D、94

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香港之所以“上天”（建设高层建筑）、“下海”（填海造地），是因为( )

A．建筑水平高

B．资金充足

C．人多地少

D．眼光远大

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急性白血病患者血小板输注指征是（）。

A.PLT<20×10⁹/L

B.PLT<50×10⁹/L

C.PLT<30×10⁹/L

D.PLT<40×10⁹/L

E.PLT<60×10⁹/L

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