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问题 单项选择题

二进制数101100101001转换成十进制数是

A．33488

B．2857

C．44894

D．23455

答案

参考答案：B

解析： 二进制整数转换成十进制整数的方法是按权展开。

填空题

函数f（x）的定义域为A，若x1、x2∈A且f（x1）=f（x2）时总有x1=x2，则称f（x）为单函数．例如，函数f（x）=2x+1（x∈R）是单函数．下列命题：

①若函数f（x）是f（x）=x2（x∈R），则f（x）一定是单函数；

②若f（x）为单函数，x1、x2∈A且x1≠x2，则f（x1）≠f（x2）；

③若定义在R上的函数f（x）在某区间上具有单调性，则f（x）一定是单函数；

④若函数f（x）是周期函数，则f（x）一定不是单函数；

⑤若函数f（x）是奇函数，则f（x）一定是单函数．

其中的真命题的序号是______．
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单项选择题

Air France SA said Monday that its second-quarter net profit fell 35 percent to 57 million ($57.4 million), but sales were steady and operating profit surged.
Earnings before interest and tax, a measure of operating income, gained 86 percent to 141 million as fuel costs fell and cargo traffic rose. Air France has been hurt less than rivals such as British Airways PLC and Lufthansa AG by the slowdown on North Atlantic routes following the war on Iraq in 2003 because it has fewer flights in that market.
Net income fell as the airline paid deferred taxes that came due. Sales rose 0.9 percent to 3.2 billion. The carrier lost about 80 million in revenue because of a four-day strike by pilots in September. An accord was reached tying future pay increases to inflation. The carrier said that first-half fuel costs fell 15 percent to 680 million. Cargo traffic rose 11 percent in the second quarter, while passenger traffic rose 1.1 percent. The airline’ s shares gained 87 cents, or 7.7 percent, to close at 12.11.
Separately, Air France and Alitalia SpA agreed to buy 2 percent stakes in each other as Europe’s second-and sixth-largest airlines deepen their partnership.

Why did Air France’s net income fall despite rising sales

A．Because it had to pay deferred taxes that came due.

B．Because the French market was shrinking.

C．Because of a four-day strike by pilots in September.

D．Because the Iraqi war had reduced Atlantic flights.
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