You said:

you've been bragging about your good command of the language...

Have I ?. Well if your idea of bragging is the correct usage of the lingua franca in this forum, then I plead guilty as charged.

However, should I descend into the realms of sloppiness that you and some others using this forum exhibit (they know who they are), whilst professing to be teachers of English, both native and non-native, I am sure you will be amongst the first to point it out.

If you teach to the same standard of English that you demonstrate in your posts, may I say that 'the blind leading the blind' was never a good idea.