When talking about past experience, what is the difference between these two sentences?        Have you gone to Hong Kong?   Have you ever gone to Hong Kong?
Both are in the present perfect, but one uses the verb 'to go' and the other 'to be'. Is there a rule for this?  Is there any chance that the differences between "I have been" vs. "I have gone", are differences in English dialect (I don't know if this is the right word).  Edit Could I say that North American English speakers use "I have gone", and maybe U.K speakers say "I've been"? Or vice versa.
I don't understand an answer. Should I add a comment, or post a new question? I recently (today) asked a question that received what seems to be a clear, concise answer, but one that's beyond my ability to understand (I'm at the cut-and-paste stage with JavaScript, and the answer seems to assume more knowledge than I actually have).  Is it considered better to ask follow-up questions as comments to the answer given, or should I post "fresh" questions to Stack to help me understand the answer that's been given? Why Faces eat each other? For , his accounts tab shows three entries for "Database Administrators". It's the same account listed three times: I went for B1 U.S. Visa at the U.S. Embassy in Delhi.   Interviewer: *Good Morning*. Me: *Good Morning* Interviewer: *What is your designation?* Me: *I am a Software Engineer.* Interviewer: *What is the name of your company?* Me: *It is XXX (I replied).* Interviewer: *What is the name of your client?* Me: *It is YYY (I replied).* Interviewer: *Have you ever been to U.S. before?* Me: *NO* Interviewer: *Have you ever been abroad before?* Me: *NO*   At this point he rejected my Visa with letter mentioning 214 (b) as the reason. I don't know why he actually rejected it.  But, I have decent 2+ years of experience with my company. And, I was going on a business meeting with the client. I would have come back after 2 weeks.  I don't know if re applying will help. Ubuntu Server 20.04 Nvidia Driver Dependencies I had a hard time installing Nvidia drivers in a fresh install of Ubuntu 20.04.  Installing via sudo apt install nvidia-driver-430 resulted in a list of 542 packages to install.  I ended up spending a bit of manual effort to get the Nvidia-provided driver installed without nearly so many dependencies (only had to install gcc and make).  Is this massive number of dependencies normal for Ubuntu Server?  I did a very vanilla install without the GUI.  Reddit suggested I ask here, as their opinion is that I should just install from the default repos, but I felt that so many packages was absurd just to install a driver.  Edit for clarity: installing the nvidia-driver-430 package appears to install the entire Gnome shell, which I feel is unnecessary on a server. What are the differences between rings, groups, and fields? Rings, groups, and fields all feel similar. What are the differences between them, both in definition and in how they are used? Is there a way in blender or an addon that allows me to select a bunch of faces (or verts) and evenly distributes (or relaxes) them into quads clean quads.  Without screwing up the vert ID/order.  Edit: I would like to have the shapes of my quads to turn into perfect squares while maintaining the volume of the object and the vertex order. amsalpha-like bibtex style with manual labels Just started blender, following the donut tutorial. Using Blender 2.8. made another donut to practice, when adding Lights I can't find the 'Use Nodes' in the Light settings. Some help would be appreciated &lt;3 Find eigen values of $B = \begin{bmatrix} 0 & A^* \\ A &0 \end{bmatrix}$ $$B = \begin{bmatrix} 0 &amp; A^* \\ A&amp;0 \end{bmatrix}$$  I think that $\det(B) = \det(A) * \det(A^*)$ and probably eigen values just get squared. What is the right answer?  EDIT: $\operatorname{rank}(B) = 2 * \operatorname{rank}(A)$, so there are twice more eigenvalue or their multiples. And the additional eigenvalues are just negatives of the eigenvalues of $A$ (Thanks to Simon).  Still can't figure out. example of not surjective isometry on a bounded not closed set. The total number of subsets is $2^n$ for $n$ elements In my probability book, it says that to count the total number of subsets of n elements is a process of $n$ stages with binary choice of either adding this element to the subset or not to add it. Therefore, the total number is $$2^n$$  But, for instance, we have 3 elements, according to this formula, there are 2 to the power of 3 elements, namely 8, which are $${\emptyset},A,B,C, AB, AC, BC, ABC$$  However, I have a hard time of imagining the process or N stages binary choice that form this many subsets. Can anyone explain/help me to understand it? I mean, ABC, if we are making the choice of A, put it in or do not put it in, exactly which subset are we choosing to put in or not? Thank you. How do I find this limit: $\lim_{n\to\infty} \left[ n-{n\over e}\left(1+{1\over n}\right)^n \right]$? Recently I booked a flight using my points. I am  planning to fly to Seattle WA from Indianapolis Indiana.  Stop over is Chicago.  On the day of my flight I am supposed to be in Chicago.   So I was wondering if I can directly board my Seattle flight from Chicago thereby not showing up in Indianapolis.  Is this okay?  Will United airlines cancel my entire journey if I do not show up in Indianapolis? What are the advantages of 10-bit monitors? To support 10-bit color the following are needed:   A monitor supporting it. A GPU supporting it (only AMD FirePro and NVIDIA Quadro support this?). Compatible software. Unless I am mistaken there are very few programs out there supporting 10-bit color. Photoshop is a notable example.   The questions are about how 10-bit monitors perform in comparison with 8-bit monitors:   In which situations would a 10-bit monitor give a noticeable advantage over an 8-bit monitor (say, for professional photography)? Have 10-bit monitors been compared against 8-bit monitors based on subjective or objective tests? What were the results? Human eyes can see only 10m colors, so would using a monitor with 1b colors make a difference? Find out which process is locking a file or folder in Windows Why are SO participants so unfriendly? I am taking my first dive into testing a mobile app.  It will be available to iOS and Android.  I've been searching for a way to test and automate iOS without having an actual iPhone or any other Mac device.  We run Windows here at the office.  I was looking to use iPhone emulators but it doesn't seem possible.  I saw Appium Studio/SeeTest but it seems even that requires iTunes and a real device.  I know you can set up a Mac vm on a Windows machine but are there any other ways to test iPhone without having to do this? When does $(e^a)^b = e^{ab}$ hold? For a complex number $A$ and a real number $B$, when does the well-known formula $(e^A)^B = e^{AB}$ fail? Or does it hold at all for complex A?     Since $e^{2\pi i} = 1$, if this formula holds for all complex numbers $A$ and real numbers $B$, then it would imply that $e^{2\pi ti}=( e^{2\pi i} )^t = 1^t=1$ for all $t$, which is obviously false. What is a terminal and how do I open and use it? What is a terminal? How do I open a terminal window? How do I use the terminal?