All the students were tired, but _____ o_爱下问搜题

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问题选择题

All the students were tired, but _____ of them stopped to have a rest. [ ]

A. both

B. none

C. any

D. neither

答案

答案：B

解答题

已知函数f(x)=cos(x-

)．
（Ⅰ）若f(α)=

，求sin2α的值；
（II）设g(x)=f(x)•f(x+

)，求函数g（x）在区间[-

]上的最大值和最小值．

单项选择题

自动扶梯应优先采用的角度是()

A．27．3°

B．30°

C．32．3°

D．35°