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问题 选择题
对于下列四个命题：①sin(-
π
18
)＞sin(-
π
10
)；②cos(-
25π
4
)＞cos(-
17π
4
)；③tan138°＞tan143°；④tan40°＞sin40°．其中正确命题的序号是（　　）
A．①③B．①④C．②③D．②④
答案

①f（x）=sinx在[-

π
2
，0]上为增函数，故sin(-
π
18
)＞sin(-
π
10
)；

②cos(-

25π
4
)=cos
π
4
=cos(-
17π
4
)；

③f（x）=tanx在（

π
2
，π）上单调递增，故tan138°＜tan143°；

④在（0，

π
，2
）上，tanx＞sinx，tan40°＞sin40°．故正确的为①④．

故选B．

单项选择题

混凝土养护应注意夏天保持必要湿度，冬天保持必要温度，其主要原因是()。

A.增加混凝土中游离水 

B.增加混凝土抗渗能力 

C.延缓混凝土凝结时间 

D.使水泥水化作用正常进行
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阅读理解

阅读理解。

                              Types of the Shanghai Expo 2010 Tickets and Regulations

1. _____ can get a Special Admission ticket for himself/herself. [ ]

A. A 56-year-old bus driver

B. A school girl with her valid student card

C. A policeman in his forties

D. A U.S. army officer on active duty

2. If you want to enter the Expo Park once every week in one month and don't want to bother to buy the

    ticket each time, you can buy a _____ ticket.[ ]

A. Single Day Admission

B. Special Admission

C. 3 Day Admission

D. 7 Day Admission

3. The function of the table is to _____. [ ]

A. remind the public of the difficulty buying the Expo tickets

B. show which groups of people can get admission into the Expo Park

C. provide information about the Expo tickets and regulations

D. introduce all the visiting regulations in the Expo Park

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