碰

He hit his head against the door. / He banged/bumped his head on/against the door.

damage sth in a collision

knock sth over

knock sb down

The couple sat with their shoulders touching.

The bowl was so hot that I dared not touch it.

His feet touched the bottom of the sea.

The bubble burst at a mere touch.

Don't touch me!

He has had no end of problems recently.

I didn't see him the last time he was here to make a speech.

In Thailand our paths crossed several times. / We have met on several occasions in Thailand.

knock against/bump into/come across/run into an acquaintance; meet an acquaintance by chance

run into trouble

run up against difficulties

Let me go and try my luck; he might be seeing patients today.

take a chance

He is a powerful person and no one dares to offend him.

She is very bad-tempered and touchy.