[nǎi]
[动]
(是; 就是; 实在是) be; be really; be indeed
Failure is the mother of success.
失败乃成功之母。
[副]
(于是) so; therefore; hence
It was a steep climb, so we rested for a while halfway up the hill.
因山势高峻,乃在山腰休息片时。
(才) only then
I didn't know it until now.
今乃知之。
You can make progress only if you are modest.
惟虚心乃能进步。
[代]
(你; 你的) you; your
your father
乃父