top-gear speed on gradient

例句：

1. 1. The car was able to reach the top gear at the steepest part of the hill.
   这辆车在山最陡峭的地方达到了最高速度。
2. 2. The driver had to slow down to maintain top-gear speed on the gradient.
   司机不得不减速以保持最高速度通过坡度。
3. 3.The race car reached its top-gear speed on the gradient, leaving the other cars far behind.
   赛车在坡度上达到了最高速度，其他车辆远远落在后面。