题目

Tom is fat. The doctor asks him to ______ and ______.A. eat more, exercise more B. eat less, exercise lessC. eat less, exercise more D. eat more, exercise less 答案：【答案】C【解析】试题分析：句意：你太胖，为了健康，你应该少吃和多锻炼。结合语境，故选C。12．设等差数列{an}的前n项和为Sn，且满足S19＞0，S20＜0，则$\frac{{S}_{1}}{{a}_{1}}$，$\frac{{S}_{2}}{{a}_{2}}$，$\frac{{S}_{3}}{{a}_{3}}$，…，$\frac{{S}_{19}}{{a}_{19}}$中最大项为（　　）A．$\frac{{S}_{8}}{{a}_{8}}$B．$\frac{{S}_{9}}{{a}_{9}}$C．$\frac{{S}_{10}}{{a}_{10}}$D．$\frac{{S}_{11}}{{a}_{11}}$