用钢笔写，不要用铅笔。

Write in ink, not in pencil.

youdao

请你不要用铅笔写好吗？

Would you mind not writing with a pencil?

youdao

请不要用铅笔写。

Don't write in pencil, please.

youdao

And, following a test, a lot of people write in pencil: don't try to erase something and bring it back and say that, oh, actually, this is what I had because we look at that and go, this is perfect.

还有，在测试的时候，很多人用铅笔：,不要试图擦掉什么，把它带回,说，事实上，这是我的,因为我们看了一下就走了，这很完美。

麻省理工公开课 - 固态化学导论课程节选