graphite apex seal

例句：

1. 1. The graphite in the mine is very soft and can be easily scratched.
   矿井里的石墨非常软，很容易被刮伤。
2. 2. Graphite is used to make pencils and other writing instruments.
   石墨被用来制作铅笔和其他书写工具。
3. 3. The graphite was extracted from the mineral by a team of scientists.
   科学家团队从这种矿物中提取了石墨。