求翻译：　　“车背驮着的车因为只有车轮跟下面的平板连在一起，万一发生磕碰，或者转弯，自卸车很不稳定，易摇晃，严重时会被甩下来，如果上面还要坐人更危险了。”一位高速交警说。是什么意思？

　　"Piggyback because only the wheels of the car with the car plate connected together below, in case of a bump, or turning, Tipper is very unstable, easily shaken, serious will be throwing down, if also more dangerous to sit on top. "One high speed traffic police said.