from scratch

例句：

1. 1. We need to start from scratch and build our own house.
   我们需要从头开始，自己建造房子。
2. 2. The new manager made a start from scratch and has already made some improvements.
   新任经理从零开始，已经取得了一些改进。
3. 3. The company decided to make a start from scratch and develop a new product line.
   公司决定从头开始，开发一个新的产品线。