length by length

例句：

1. 1. We need to work on ourskills one length by length.
   我们需要逐段提高我们的技巧。
2. 2. The project will be completed insteps by steps.
   这个项目将分阶段完成。
3. 3. Sheis learning to walk by length by length.
   她正在逐段学习走路。