题目

The  driver  was seriously hurt in  the  traffic  accident. We  must send   him  to  the hospital __ . A. on time  B. at first  C. at last  D. right away 答案：D已知函数f(x)=2sin(x+π6)-2cosx，x∈[π2， π]．（1）若sinx=45，求函数f（x）的值；（2）求函数f（x）的值域．