To have unrealistic or impractical plans or dreams.
有不切实际或不实际的计划或梦想。 (Yǒu bù qiè shí jì huò bù shí jì de jì huà huò mèng xiǎng.)
"She’s always building castles in the air, dreaming of a perfect world."
"她总是在空中建造城堡，梦想着一个完美的世界。" (Tā zǒng shì zài **kōngzhōng jiànzào chéngbǎo**, mèngxiǎng zhe yīgè wánměi de shìjiè.)
to argue about small or unimportant details
To relax and not worry too much.
to study or explore something in great depth
to collaborate with someone for a common goal
To achieve something very difficult or seemingly impossible.
A true friend tells you harsh truths to your face.
