题目

Schools across China are expected to hire 50,000 college graduates this year as short-term     teachers, almost three times the number hired last year, _____reduce unemployment pressures.    A. help                   B. to have helped          C. to help              D. having helped 答案：C已知函数，（1）求函数f（x）的最小正周期；（2）求函数f（x）的单调减区间；（3）画出函数的图象，由图象研究并写出g（x）的对称轴和对称中心．