Wearing, wore

I guess it depends. When you saw him/her wearing a blue cap, then he was wearing it already and continued wearing it. On the other, if you saw him wore a blue cap, you saw him put on a blue cap.

I don't know. I can't focus today or the week following this week because I'm freaking bored. Sorry, I just had to write that. I wrote it many times in my online blogger already but that was not

I would use the first one...
When I saw you, you were wearing a blue cap.

So this sentence is right!

I knew it.

Can sb help, please? I am hallucinating!

Yes, as W said, use the first with a comma..

When I saw you, you were wearing a blue cap.

Both sentences are correct — or would be if you placed a comma between the two you's. The only difference between them is a subtle difference in connotation. Generally, the difference between "was/were + [verb]ing" and just "[verb]" is that the first implies a continued action whereas the second implies an action that did not necessarily occur for more than an instant. (For example, "I was jumpin

i agree with kitkat, that both sentences are correct. the past progressive, "was wearing", is far more common. i disagreee, however, that the 2nd sentence is "terse". to me it has an air of nostalgia, something of the poetic... "on the day we met/the first time i saw her, she wore a blue hat" (or whatever the original sentance was...)

He was interesting or he was being interested?. Are these two sentences correct?

Sure, poetic, fair enough. I guess it depends upon the circumstances, really.