Some literature reports that English language learners can tell the difference between idioms and proverbs. The approximate meaning of a proverb can be worked out from the words in the sentence. However, the meaning of idioms cannot always be defined by the learner’s knowledge of the words in the phrase, even if they know every single word.
I’m not sure I agree with that. Have a look at the following. What do you think?
‘Has the cat got your tongue?’ means ‘Why are you keeping quiet about something?’
‘You look like the cat that got the cream’ means ‘You look very happy or satisfied about something’.
‘To let the cat out of the bag’ means ‘To accidentally disclose a secret’.

