Comment Re:Example (Score 2) 75
someone who is not familiar with words having different modes
The problem is, that if you don't know these basic constructs in your native language then you're not really fluent in it. You might think you can speak it fluently - but you're not well enough educated if you lack the basic rules.
Sadly this is very common: just look at all the internet content that confuses they're, their and there. Or mistakes "have" for "of" in written form.
Perhaps Duolingo should have a qualification test to screen out people who weren't paying attention at school (as all these topics are taught, in every english-speaking school) and it could sign them up for a remedial english class, instead.