在△ABC中,12cos2A=cos2A-cos A.(I)求角A的大小;(II)

题型:解答题

问题:

在△ABC中,
1
2
cos2A=cos2A-cosA

(I)求角A的大小;
(II)若a=3,sinB=2sinC,求S△ABC
考点:正弦定理解三角形余弦定理
题型:解答题

在2009年10月1日,新的饮用矿泉水强制性国家标准《饮用天然矿泉水》正式实施,其中“溴酸盐(BrO3-)”这一潜在致癌物质被做了严格限制。有关专家解释,矿泉水在开采过程中会含有少量溴化物(Br),在后续的生产过程中经臭氧(O3)处理逐渐转化成溴酸盐。下列有关该转化过程的认识正确的是(  )

A.该过程中溴化物(Br)得到电子

B.该过程中臭氧(O3)是氧化剂,溴酸盐(BrO3-)是还原剂

C.该过程中溴元素被还原,氧元素被氧化

D.该过程中溴元素发生氧化反应,氧元素发生还原反应

题型:解答题

阅读理解。

      Lucy studies in a middle school. She is ten years old. She has a little brother. His name is Bill. Bill is

only three. Lucy likes him very much.

      Today is Sunday. Lucy wants to do her homework. She takes out her pencil-box and opens it.  "Oh,

dear! Where's my pen?" She can't find her pen. She goes to ask her brother in his bedroom.

     "Bill! I can't find my pen. Can you see...Oh, what are you doing with my pen? "

      "I'm writing to my friend, Peter," Bill answers.

      "But how can you? You don't know how to write!"

     "It doesn't matter. Peter can't read," Bill says.

1. How old is Lucy's brother?       

A. Five.      

B. Four.        

C. Six.        

D.  Three.

2. ______ can't find her pen.    

A. Nancy    

B.  Peter    

C. Lucy    

D. Bill

3. What is Bill doing? He is______.     

A. playing   

B. drawing    

C. writing    

D. singing

4. Which is not right?    

A. Lucy finds her pen in Bill's room.

B. Bill can't write.

C. Bill is writing with Lucy's pen.

D. Peter can re-ad.

5. Bill and Peter are______.   

A. friends    

B. English    

C. students    

D. school girls

题型:解答题

抑癌基因p53的功能是()

A.抑制细胞周期从G1 期进入S 期

B.维持基因组的稳定性

C.诱导细胞凋亡

D.抑制致癌基因

题型:解答题

对下列公益广告运用的修辞方法的作用理解不正确的是(   )

A.别踩,我怕疼。(“爱护草坪”公益广告)

理解:运用拟人的修辞方法,表现小草柔美的身姿、娇贵的情态。

B.说好普通话,“知音”遍华夏。(“推广普通话”公益广告)

理解:运用夸张的修辞方法,突出了学好普通话的显而易见的好处。

C.为何血浓于水?因为爱在其中。(“无偿献血”公益广告)

理解:运用设问的修辞方法,引发思考,呼唤救死扶伤、无私奉献的大爱。

D.带上平安上路,载着幸福回家。(“交通安全”公益广告)理解:运用对偶的修辞方法,表达了对人们出行平安、生活幸福的美好祝愿。

题型:解答题

下列选项中,客货运输车辆的安全运行要求包括( )等。

A.运输车辆的安全要求

B.旅客运输安全运行要求

C.货物运输安全运行要求

D.客货运输车辆驾驶人安全运行要求

E.紧急事故处理的安全运行要求

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