他说了半天，我还是不懂。

Tā shuō le bàntiān, wǒ háishi bù dǒng.

He talked for a long time, but I still didn’t understand.

我找手机找了半天。

Wǒ zhǎo shǒujī zhǎo le bàntiān.

I looked for my phone for a long time.

他想了半天才回答老师的问题。

Tā xiǎng le bàntiān cái huídá lǎoshī de wèntí.

He thought for a long time before answering the teacher’s question.