Prepare N pieces of the basic same paper, stopwatch, meter scale, etc. (See the picture below).

完整平整的基本相同纸n张、秒表、米尺等(见下图)。

youdao

Prepare N pieces of the basic same paper, stopwatch, meter scale, etc. (See the picture below).

完整平整的基本相同纸n张、秒表、米尺等(见下图)。

youdao