*to find the knack of doing sth
*to know a good way of making money
*That's it, i've got it.

*What on earth is that thing?‏¹
*There are loads of things to do in the house.
*It's not bad, that thing of yours.
*Pass me the thingummy/whatsit on the table.

*There's something wrong.
*They told us some dreadful things.
*I've just thought of something.

*Cycling is not my thing.
*What I love are holidays in the country.
*It was a fantastic house, enourmous, by the sea, do you get the idea?

*the trick of the trade
*There's a trick to it.

Qu'est-ce que c'est que ce truc?