4 sentences

1. 那个坏孩子终于学好了。

   nà gè huài hái​zi zhōng​yú xué​hǎo le.

   That naughty boy has finally turned over a new leaf.

   Source: Dong Chinese Dictionary

2. 要学好一门外语，首先要有信心。

   yào xué​hǎo yī mén wài​yǔ, shǒu​xiān yào yǒu xìn​xīn.

   To learn a foreign language well, one must first have confidence.

   Source: Dong Chinese Dictionary

3. 要想学好这门手艺，必须得先入其门。

   yào xiǎng xué​hǎo zhè mén shǒu​yì, bì​xū děi xiān rù qí mén.

   To master this craft, one must first learn the basics.

   Source: Dong Chinese Dictionary

4. 我一定要学好中文。

   wǒ yī​dìng yào xué​hǎo Zhōng​wén.

   I must master the Chinese language.

   Source: Dong Chinese Dictionary