半天 (bàn tiān): half a day, a long time

I waited for half a day before he came.

Mom spent half a day cooking.

He thought for a long time, but couldn't figure out the answer.

We haven't seen the sun for half a day.

He works a half-day shift every day.

I looked for quite a while but still couldn't find the keys.

She thought for a long time before answering.

We waited ages, and the bus still hasn't come.