a few questions...

[ruofei]

Hello teachers,
I hope you're fine. Here I come with a few questions:

1) I don't feel well since my brother left/ I haven't felt/ I haven't been feeling well since he left
(are the 3 of them acceptable? What's the difference?)

2) Being little isn't that bad!
- Yes, it is!
- it' not!
- Is too!
(what exactly is the meaning of this last one?)

3) Dan is tired, he's been working all day/ he's worked all day.
(rather continuous form? why?)

4) Can we 'when I last saw her' by 'the last time I saw her' and 'Last time I saw her'?

5) I was rude to my brother and I regret/I'm regretting
(simple or continuous form?)

Thanks in advance!

[ruofei]

And another expression, I suppose American:
"to work over the kinks"
Thanks again!

[Tdol]

1) I don't feel well since my brother left/ I haven't felt/ I haven't been feeling well since he left
(are the 3 of them acceptable? What's the difference?)

The first is wrong. The other two are fine. 'Been feeling' puts more emphasis on how you feel now as well.

2) Being little isn't that bad!
- Yes, it is!
- it's not!
- Is too!
(what exactly is the meaning of this last one?)

A collaquial way of csntradicting someone

3) Dan is tired, he's been working all day/ he's worked all day.
(rather continuous form? why?)

For emphasis

4) Can we 'when I last saw her' by 'the last time I saw her' and 'Last time I saw her'?

We can, though you've missed 'replace', and I'd use 'with'

5) I was rude to my brother and I regret/I'm regretting
(simple or continuous form?)

Simple, and say 'regret it'.

[ruofei]

Dear tdol,
Thank you for your prompt correction on this post and my other one ("I think/I believe")
And thank you for always, always taking your time to answer to as many people as you can.
Sincerely yours
Ruofei

[ruofei]

Dear tdol,
Thank you for your prompt correction on this post and my other one ("I think/I believe")
And thank you for always, always taking your time to answer to as many people as you can.
Sincerely yours
Ruofei

[Tdol]

You're very welcome, Ruofei.