题目

——Why are the tax collectors so busy?     ——Many people prefer to have their tax forms completed by a professional rather than ___. A、do it themselves B、doing it themselves  C、to do it themselves  D、done by themselves 答案：A 解析: 考查固定结构。prefer to…rather than…意为“宁愿……不愿……”，其后接动词原形。如图所示，用 AO、BO 绳吊一重物 P 静止，其中 AO 绳水平．现用水平向右的力 F 缓慢拉起重物 P 的过程中，绳 OB 所受的拉力变化为（ ）A．变大B．变小C．先变小再变大D．不变