I’ve recently heard the following sentences:
What is this tell us about the deployment of first self driving cars? What do we learning from this?
Both violate standard grammatical rules. But since it was in a speech of a professional reporter from The Economist Radio I guess there is some rule explaining why this is the valid usage.
Here is the link on the radio show (starting from 5:18).
Question: Is this a grammar mistake? If not, what is the rule behind it?
I had a listen to that. I think it’s a case of understanding the interviewer’s (US) accent. In some accents a ‘t’ is pronounced as ‘d’, but when ‘d’ is also pronounced as ‘d’, it can be confusing for non-native speakers.
You might have heard it as 1)’Whaddas this tell us… 2)Whadda we learning.
The underlying grammar is not ‘What is this tell us’ or ‘What do we learning’.
In the first ‘whaddas’ case, the ‘t’ of ‘what’ and the ‘d’ of ‘does’ blend into a ‘d’ sound, so the meaning is ‘What does this tell us‘.
In the second the ‘t’ is pronounced as ‘d’. The written version is ‘What are we learning‘ or perhaps ‘What’re we learning’.