在下列事件中:①掷一枚骰子出现4点;②买一张 * * 中特等奖;③异号两数相乘得负;④

题型:选择题

问题:

在下列事件中:①掷一枚骰子出现4点;②买一张 * * 中特等奖;③异号两数相乘得负;④边长为a,b的长方形的面积为ab;⑤掷两个普通的骰子,点数之和大于13.其中不可能事件是(  )
A.①②B.③④
C.⑤D.没有这样的事件
考点:随机事件
题型:选择题
能够把圆O:x2+y2=16的周长和面积同时分为相等的两部分的函数称为圆O的“和谐函数”,下列函数不是圆O的“和谐函数”的是(  )
A.f(x)=4x3+xB.f(x)=1n
5-x
5+x
C.f(x)=tan
x
2
D.f(x)=ex+e-x
题型:选择题

短文改错。

     Mobile phones are being more wide used. They're light in weight and easy to carry, offer fast and

convenient service for communication. The users use them for making phone call, sending short messages

and Internet-surfing. In recently years, mobile phones have become popular to middle school students.

Quite a few use it to keep in touch with their families and friends, what, of course, was of great

convenience. However, I don't think it's good to do so. In spite of the advantages mentioned above, student

users often waste a lot of time chat on the phone in their spare time. Some even cheat in exams. In addition,

mobile phone bills spend their parents lots of money.

______________________________________________________________________________________

题型:选择题

It's surprising that your brother _____ Russian so quickly-he hasn't lived there very long. [ ]

A. picked up          

B. looked up          

C. put up        

D. made up

题型:选择题

德清窑在今日的()省,六朝时,其产品的主要釉色为()色。

题型:选择题

“12CrMoV”和“12Cr1MoV”属于()。

A.碳素结构钢

B.优质碳素结构钢

C.合金结构钢

D.低合金高强度钢

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