They are both fine. Which you prefer probably depends on the context.
If you saw something strange on a table across the room, you might well point to it and ask someone:
What is there on the table?
The there indicates what you're pointing to.
If you were actually beside the table, you are more likely to ask:
What's on the table?
What's that ...
Both are fine.
What is on the table? tends to imply that you know that there is something on the table, and want to know what it is.
What is there on the table? does not have that implication: there might be something and there might not.
The implication I mentioned is not strict: you might still use the first even if you don't know whether there is ...
If I understand what you are asking, the simple answer is:
When did we decide to do something?
However, it is true that that is ambiguous: it could be asking about when we made the decision, or when the activity was to happen.
Often the ambiguity won't matter, as we are much more likely to be asking about the decision for the future than the process of ...
Perhaps the most natural question would be "Was it you [who farted]?". It would not be strange to ask "Did you [fart]?" Since there has been no mention of "hiding" previously it would be hard to understand "Are you" as meaning "are you hiding it?"
Correctness in this kind of context isn't very important. Children will pick up correct English at a young age, ...
"Did you?" is correct. It's just short for "Did you fart?"
The best way to check is just to imagine it as a full sentence, which you've seem to have already done. You can then easily see that "Are you fart?" is clearly wrong.
I think your best approach is to try to avoid asking "have you used my computer?" You could instead ask, "Do you know if anyone else has been using my computer? I noticed that [describe the reason you believe someone else has been using your computer]." Asking the question this way conveys a little bit more trust-- you're asking the second person if they ...
In this special situation, I think the most idiomatic and culturally appropriate question to ask is simply:
How are the kids?
This phrasing is less intrusive. It does not make any assumptions or convey any expectations about whether or not your friend has had or taken advantage of an opportunity to see his children. It allows him to easily answer in any ...
What is mostly used for two things:
asking for information specifying something.
"what is your name?"
asking for repetition of something not heard or confirmation of something not
"what? I can't hear you"
the thing that / things that (used in specifying something).
"what we need is a commitment"
(referring to the whole of an ...
Colloquially, we do sometimes express questions simply by tone of voice, without the inversion normally required. So
You want to chat about something?
is a perfectly good colloquial question. A neutral (less colloquial) form would be
Do you want to chat about something?
But where the modal is need, I find this option much less natural, possibly ...
Have you sent that letter?
is perfectly fine. You might consider:
Have you sent that letter yet?
to make it even more neutral because it doesn't imply that you expect that the letter was already sent.
Or, just say what you mean:
If you haven't sent that letter yet, I'd like to make some changes to
Teacher: I have recently found x.
is similar, tense-wise, to:
I have recently traveled so much.
The response would probably be something like:
Oh really? When did you last travel?
The simple past is used by the second speaker because he or she wants more specific information about a specific instance in the past.
The point is this: The present perfect ...