单看成绩，他确实进步了不少。

dān kàn chéngjì, tā quèshí jìnbù le bù shǎo.

Judging by his grades alone, he has indeed made a lot of progress.

这件事不能单靠一个人完成。

zhè jiàn shì bù néng dān kào yī gè rén wánchéng.

This matter cannot be completed by one person alone.

单从外表来看，很难分辨真假。

dān cóng wàibiǎo lái kàn, hěn nán fēnbiàn zhēnjiǎ.

Judging solely by appearance, it's hard to tell the real from the fake.