colloquium

Dear Colloquium,

Thanks for your comment in my Thread concerning 'until recently'.

So...do you suggest that the Past Simple Tense is more appropriate than using the Present Perfect Tense for the below contex?

'He worked there until recently'. ---> Correct!
'He has worked there until recently' ----> Incorrect!

Am I right here?

Thanks again ^_____^

Dear colloquium:
Some of my friends say that 'knowledge of' equals 'a knowledge of' and that as long as there's an adjective before 'knowledge of', we can always add 'a/an' to the phrase.
This American teacher says there's no difference between them:
http://www.usingenglish.com/forum/ask-teacher/84380-knowledge-knowledge.html

And this British teacher says there's a difference:
http://www.usingenglish.com/forum/ask-teacher/56095-knowledge-knowlegdge.html

Though I've spent quite some time studying these phrases, I'm not sure I understand the use well.

I'm hoping you can help me with this. Thank you in advance.

hi, tnx so much 4ur help...

Ps.Please participate in the vote 'Would you like to live in the USA?'. We need to see your beautiful opinions about living in the USA! Hopping that you'd set the stage for having a good conclusion!