Corpora

Other resources I want to talk about are corpora. According to en.wikipedia.org "in linguistics, a corpus (plural corpora) or text corpus is a large and structured set of texts (nowadays usually electronically stored and processed). they are used to statistical analysis and hypothesis testing, checking occurrences or validating linguistic rilus within a specific language territory". Therefore, between this compendium of texts we can find expressions and it can help us to be sure about their meanings and correct uses. 

I've try with the expression "a shoulder to cry on" and I've introduced it in two corpora, http://corpus.byu.edu/bnc/ and http://www.linguee.es/. 

In the first one, I've found 11 pieces of writing where it appears, so we can see in which contexts we can use it, like "And you promise that if you need a shoulder to cry on, you'll come to me first?". 

In the second one, apart from these kind of examples, there is the translation. For intance, in the first column there is: "they need a shoulder to cry on or someone to boost them up", and in the second "necesitan un hombre en el que llorar o alguien que les levante el ánimo". 

Now, you must try with the expression you choose!