magnetic picture tracing

例句：

1. 1. The magnet attracts iron filings.
   磁铁吸引铁屑。
2. 2. The new car has a magnetic key.
   新车有一个磁性钥匙。
3. 3. The magnet can be used to align the screws.
   磁体可以用来对齐螺丝。