下列变形正确的是（　　）

已知△ABC中，AB=3，AC=2，点D在边BC上，满足 $\frac{\overrightarrow{AD\cdot }\overrightarrow{AB}}{\left|\overrightarrow{AB}\right|}$ = $\frac{\overrightarrow{AD\cdot }\overrightarrow{AC}}{\left|\overrightarrow{AC}\right|}$ ，若 $\overrightarrow{AB}$ = $\overrightarrow{a}$ ， $\overrightarrow{AC}$ = $\overrightarrow{b}$ ，则 $\overrightarrow{AD}$ =（  ）

    My family is ____(计划) a journey to China in the winter. Our first ____(选择) is to visit Beijing, one of the____(大) places in the world.. So we need to ____(预订) the plane tickets. To tell you the truth, we like going by train____ (好) . But we think it is too slow and it ____(花费) much time. Though going by plane is more____(昂贵的)，it goes____(快) and saves time. Some people may think it's not ____(安全) , but our family all____(赞同)it's our favorite way to travel.