Suppose a child is accused of misbehaviour and the parent wants to know what the child has done. Would it be okay to ask the child: &quot;what have you done?&quot; or should they say &quot;what did you do?&quot;. Is there a difference in nuance? Does &quot;what have you done?&quot; sound more accusatory?
I have been learning English for 7 years now, and I have read so many grammar books with rules, telling the difference between Present Perfect and Past Simple and I still find it hard to distinguish them.   On paper, it is easy, if it is not a certain (exact) time in the past without any time markers (yesterday, a month ago, etc) it is past simple. Yes, but outside the classroom it is really harder than this . I have heard many people speaking how they want to, mixing the tenses.   So, I will give these sentences which i have heard to be constructed differently, please, if someone can explain the difference to me.     Have you enjoyed the party? / Did you enjoy the party?      I have given the documents today. / I gave the documents today.      I have done this when I have revised it. / I did it when I revised it      What did you do today? / What have you done today ?   Is it possible to use past simple without mentioning a definite time in the past  (without the time markers)?     It has been 3 years since we moved house. / It has been 3 years since we have moved house.      I know him since we met each other/ I know him since we have met each other   Correct me if some of the sentences are grammatically wrong!
Convert Shapefiles to GeoJSON? I'm trying to convert Shapefiles from the  website into a GeoJSON file for use with Google Maps API. I'm using QGIS to facilitate but I can't get the projection/coordinates right. So far I've tried Google Mercator (EPSG:900913) and WGS 84 (EPSG:4326) with no luck. I'm using the OpenLayers to verify results and it keeps placing Texas near the  Gulf of Guinea (0 lat, 0 lng). I have looked through several questions and answers on EL&amp;U, and often there is an indication that American English prefers "have" while British English prefers "have got". In addition, there are several references to "have got" being more informal than "have" (e.g.: , ). But where is it considered more informal? In American English alone or both American and British English?   This point may seem obvious to those who made the above mentioned references, but the fact is that even the most fluent users of English in my country will say without a doubt that 'have got' is the preferred usage in the UK and, therefore, it must also be more formal. Why? Because in an academic environment, the more informal structures are generally frowned upon, outside some specific spoken exercises. And if the teachers insist on using "have got", it follows it isn't informal.  So, is the teaching of (British) English in our schools transmitting the wrong idea?  EDIT: I'm adding some information in answer to the comments.  I'm mainly concerned with the idea of possession:      I have got a cat vs. I have a cat and She has got a dog vs. She has a dog   As mentioned in the comments, every (Portuguese) student will be told that "have" and "have got", when it comes to the idea of possession, are absolute synonyms, the only two differences being:    "have got" is preferred by British English, "have" is preferred by American English   the negative and interrogative structures differ    I have never heard of any distinction in formality. In fact, I was rather surprised when I went through the EL&amp;U archives and read about it.  So, would "I have got a cat" be as formal/informal as "I have a cat"?   And how do British and American English look at its formality/informality? Is it the same? Vitali-type set with given outer measure Default route lost on reboot The problem with reputation: does high reputation attract too many upvotes? It's not that I feel bitter when somebody else's answer is upvoted above my own, but it's when a user with a high rep answers a question and their answer seems to attract an immediate barrage of upvotes.  Now I'm not saying that these votes are always unwarranted, but by simply observing this behavior, I think the system seems flawed.    The concept of reputation (or at least one of the concepts) is to give users a sense of trust in the reputed user's answers.  But this should be trust, not blind faith.  I know that this problem doesn't exist for every question asked on SO, but it's definitely present.  I'm sure this is a contentious question, as it might seem overly critical, but does anybody else agree with me and, if so, does anybody have any thoughts on how this problem could be alleviated? It's a great shame when a new or less active user's answer is stifled by the reputation-rich user's answer. What's a common interjection for the reaction to something creepy and disgusting (like some insects or spooky places, etc.)? Short story about a robot who wants to become a writer Where did my default brushes go? I was working on a logo design for a client in Illustrator CS4 when suddenly the default brushes were no longer there. The brush files are still in place but they do not show up in the brushes panel. The options to show the brushes by type are checked but greyed out.   I tried a preference reset, that didn't fix it. I haven't tried any new brushes because the brush I needed was in the stock set. I know its bad form not to try everything but I needed one of the stock brushes to tweak an existing design. Gradient and Swiftest Ascent I want to understand intuitively why it is that the gradient gives the direction of steepest ascent. (I will consider the case of $f:\mathbb{R}^2\to\mathbb{R}$)  The standard proof is to note that the directional derivative is $$D_vf=v\cdot \nabla f=|\nabla f|\,\cos\theta$$ which is maximized at $\theta=0$. This is a good verification, but it doesn't really help me understand the result. What component to use for audio signal switching? I'm looking to build a guitar pedal switcher based on a Raspberry Pi or Arduino (have not yet decided, but I have an unused Raspberry around and I lean towards that). Anyway, digital logic.  Now, I need to switch audio signal obviously and I need to do it quietly (both physical silence and electrical silence). Please note that the signal is line level throughout most of the build, except for the input which is much lower. I will probably have 2 or 3 loops before the preamp so those may not encounter line level signal.  From what I read and know, so far, mechanical relays are not really an option due to the clicking noise they make. I also read something about FETs, but that's a bit out of my league and I would appreciate any info on these.  PS: I will probably use different power rails for the digital and analog paths.  PS2: The whole thing will be mounted in a 1U rack enclosure, so please tell me if I should take into consideration any thermal issues. How to load up CSS files using Javascript? Is it possible to import css stylesheets into a html page using Javascript? If so, how can it be done?  P.S the javascript will be hosted on my site, but I want users to be able to put in the &lt;head&gt; tag of their website, and it should be able to import a css file hosted on my server into the current web page. (both the css file and the javascript file will be hosted on my server). Case-sensitive Google search Is there any way to make a Google search case-sensitive? Do subdomains help/hurt SEO? If I have example.com, and blog.example.com, do search engines see those as one site or two? Will using subdomains hurt SEO? I have some technical reasons why I can't use example.com/blog. Proof that the irrational numbers are uncountable Can someone point me to a proof that the set of irrational numbers is uncountable? I know how to show that the set $\mathbb{Q}$ of rational numbers is countable, but how would you show that the irrationals are uncountable? Proof of triangle inequality How to install Minecraft (Client) How to correctly install Minecraft, including setting any needed packages or apps to install it and to troubleshoot the most common problems that Ubuntu users face when trying to use Minecraft.  I am trying to install and run Minecraft without first having to install the Oracle version of Java. I want to use the OpenJDK version that comes with Ubuntu and as a last resort, use the Oracle one.  I also want to know a list of problems related to Minecraft in Ubuntu and the possible solutions to them.  A step by step guide on how to install Minecraft would also help. It looks like we'll be adding  support to Stack Overflow. This is necessary to prevent bots, spammers, and other malicious scripted activity. We only want human beings to post or edit things here!  We'll be using a JavaScript (jQuery) CAPTCHA as a first line of defense:    The advantage of this approach is that, for most people, the CAPTCHA won't ever be visible!  However, for people with JavaScript disabled, we still need a fallback and this is where it gets tricky.  I have written a  which we can re-use.    However, I'd prefer to go with something textual to avoid the overhead of creating all these images on the server with each request.  I've seen things like..   ASCII text captcha: \/\/(_)\/\/ math puzzles: what is 7 minus 3 times 2? trivia questions: what tastes better, a toad or a popsicle?   Maybe I'm just tilting at windmills here, but I'd like to have a less resource intensive, non-image based &lt;noscript&gt; compatible CAPTCHA if possible.  Ideas? A student of mine has been self-studying some elementary number theory. She came by my office today and asked if I had any hints on how to prove the statement      If $m$ is odd then $\gcd(2^m-1,2^n+1)=1$.    It's been a while since I took number theory and I'm not sure what to do. She said she is learning about congruences, primitive roots, and power residues.  She has not taken any group theory. The subscript size for formulas in beamer presentation First of all sorry because this question may be duplicated. I don't know why the question was uploaded with another user's name and I can't edit it (may be you can delete the previous question with the same title). The question is the following:  I am creating a beamer presentation where I have a lot of formulas. Between the packages used I have \usepackage{amsmath} and the theme for the presentation is \usetheme{Warsaw}.  As it can be seen in the attached picture, the size of the sub(super)script is bigger than the normal writting.     Anyone knows a set of basic packages in order to get the classical formulas, without these size changes?  The code is the following  \documentclass[]{beamer}  \setbeamercovered{transparent}   %--------------------------% % To add enumeration index %--------------------------% \addtobeamertemplate{navigation symbols}{}{%     \usebeamerfont{footline}%     \usebeamercolor[fg]{footline}%     \hspace{1em}%     \insertframenumber / \inserttotalframenumber  } \setbeamercolor{footline}{fg=black} \setbeamerfont{footline}{series=\bfseries}   %---------------------------------------------------------------------------------%  \usepackage{amsmath,amssymb}    % Theme for the presentation \usetheme{Warsaw} % Change the colour \usecolortheme{spruce}  \setbeamertemplate{footline}{}  % Delete the footline with the names    \begin{document}    \begin{frame} \frametitle{\textbf{Algorithm}: step \texttt{s}}   \scriptsize  \textbf{STEP \texttt{s}}  \vspace{0.25cm}  Let $B^{(s-1)}$ be the variable  for the $\mathit{(s-1)}$-th step, let's take the sets $I_+^{(s-1)}$ and $I_-^{(s-1)}$ of length $r_+^{(s-1)}$ and $r_-^{(s-1)}$ respectively,and define:\\  \vspace{0.25cm}  \begin{center}  $B^{(s+)}= \sqrt{\tfrac{(r_+^{(s-1)} + 1)*r_-^{(s-1)}}{r_+^{(s-1)} + r_-^{(s-1)} + 1}} $  \end{center}   \end{frame}  \end{document} Can anyone help me with a solution? Write down the assumptions in a form of clauses and give a resolution proof that the proposition                               $$\Big((p \rightarrow q) \land ( q \rightarrow r) \land p \Big) \rightarrow r$$  is a tautology.