keep level up

• 保持水平

keep level up的用法和样例：

例句

1. Level out and fly straight and level.
   拉高机头保持水平直线飞行。
2. In a trot the forequarters and hindquarters are mutually coordinated while the back remains level, firm and relatively motionless.
   小跑的时候前半部和后半部相互地调整，背部仍然保持水平，稳固的和相对不动的。