How can we tell if a sentence is expressing contrast?
How to express contrast between two things?
Can I say these three words in this sentence are expressing contrast?:
In 1997, France passed a law banning the use of English words in official contexts if an equivalent French expression existed – but the law seems to be honored more in the breach than in the observance.
You will know that a sentence expresses a contrast by merely looking into the conjunction used in the sentence. A conjunction is a connecting word. One of the kinds of conjunction is the adversative conjunction. Adversative conjunctions connect words or expressions that are opposite or in contrast. Examples of these conjunctions are but, yet, still, however, while, only, etc. So, if you see one of these conjunctions in a sentence, suspect that the sentence expresses a contrast.
but is adversative (that's a big word that means 'like but'!) It says that the rest of the sentence is going to present an opposite case - it could be a comparison or a straightforward refutation or value judgement: 'In 1997, France passed a law banning the use of English words in official contexts if an equivalent French expression existed – but the law was a total waste of time.'
more...than signifies that you are making a comparison. More is a comparative - it says how something differs by being something -er than something else.