题目

In the new city there wasn’t a single person________ the poor boy could turn for help. A．that      B．who C．from whom    D．to whom 答案：D turn to sb. for help为固定句式，意思是“求助于”。已知函数f（x）=ax3+bx2，当x=1时，f（x）有极大值1．（Ⅰ）求a，b的值；（Ⅱ）求函数f（x）在区间[-12，2]上的最大值和最小值．