Are these both sentences correct? It's about permission. 1)May I use your phone, please? 2) could I use your phone; please?
"May I have a glass of water" vs. "Can I have a glass of water": which is better, "may I" or "can I", when asking for something? What is the correct sentence when asking for something like while flying asking for a glass of water :     May I have a glass of water     or      Can I have a glass of water
Should you use "who" or "that" when talking about multiple people doing something? Which of the following is correct?        There were 10 people that went to the store.   There were 10 people who went to the store.      Edit:  Which of the following is correct?        There were 10 people that had brown hair.   There were 10 people who had brown hair. Beamer: TOC only once before sections with subsections My presentation consist of multiple sections. Some sections consist of subsection and some not. I want beamer to display the TOC before every subsection and before every section which consists of no other subsection.  Currently, i write in the preamble:  \AtBeginSection[] {     \begin{frame}&lt;beamer&gt;     \frametitle{Inhalt} %     \tableofcontents[currentsection]       \end{frame} }  \AtBeginSubsection[] {     \begin{frame}&lt;beamer&gt;     \frametitle{Inhalt} %     \tableofcontents[currentsubsection]       \end{frame} }   As a result, if a section consist of subsecitons beamer displays the TOC twice before the first subsection in a section, one time for the section and one time for the subsection. That is ugly in my opinion. What can i do? Classifying whether a collection of objects is a set I'm wondering whether or not there is a definite criterion for determining whether a collection of objects is a set. In the literature, I've recently encountered some obscure examples (in Riemann Surface Theory, to be precise) of naturally-arising collections of objects which are not sets.   Here is some pseudo-rigor to make the question more precise:   Let $S$ be a collection of objects. Is there some property $P$ so that $S$ is a set iff $S$ has property $P$? using a:hover to change the color of an image How to check if an object is nullable? How do I check if a given object is nullable in other words how to implement the following method... bool IsNullableValueType(object o) {     ... }  I am looking for nullable value types. I didn't have reference types in mind. //Note: This is just a sample. The code has been simplified  //to fit in a post.  public class BoolContainer {     bool? myBool = true; }  var bc = new BoolContainer();  const BindingFlags bindingFlags = BindingFlags.Public                         | BindingFlags.NonPublic                         | BindingFlags.Instance                         ;   object obj; object o = (object)bc;  foreach (var fieldInfo in o.GetType().GetFields(bindingFlags)) {     obj = (object)fieldInfo.GetValue(o); }  obj now refers to an object of type bool (System.Boolean) with value equal to true. What I really wanted was an object of type Nullable&lt;bool&gt; So now as a work around I decided to check if o is nullable and create a nullable wrapper around obj. When I go to Settings &gt; Applications &gt; Manage Applications &gt; Downloaded I see an application list. If I select some applications I see button "Force stop" active, but some applications have this button dimmed.  What does it mean? What happens if I press this button?  This button can't mean application running, since the applications with this button are not listed in Running section.  Can I list just applications which have the Force stop button active and uninstall them?    Android version: 3.2 How to prove the set $S$ is closed under the binary operation $a*b=a+b+kab$? Let $k$ be any nonzero real number and let $S$ be all real numbers except ${-1\over k}$. Let $a,b \in S$. Define * on S by $a*b=a+b+kab$. Prove that $S$ is closed under *.  All I can think to do is set $a*b$ equal to ${-1\over k}$, but I don't know where to go from there. Is that the extent of the proof? $\mathbb Z[i]/ \langle 1+2i \rangle \cong \mathbb Z_5$ How do I go about tracking down IO usage in Linux and other *nix OS'? Occasionally, something on my system starts hammering the disk. I would like to log data that would let me know about I/O usage per process, then I could go back to it later and see what keeps doing this. How should I go about solving this problem? Bonus points for solving this for arbitrary block devices. access controller variable in javascript Is there any way to access controller variable set in a Method in Javascript. In the example above the value is set in constructor. But when I set it in a method it is showing as NULL in Javascript  In controller:  public class abc {     public string varA { get;set; }     public void fn(){         varA='hello';     } }   In VFPage:  function hello(){     var bool = '{!varA}';     alert(bool); }   The alert statement in the VF Page(i.e bool) is displayed as null. Can you please help how to access a variable set from a method instead of constructor? In chat, the short code [metaso] expands to http://meta.stacexchange.com/ (no typo, the missing 'k' is the bug I'm reporting).  (And since this is too short a bug report, I'll note that I think that [metaso] should probably point to .) Why is surface tension parallel to the interface? A text says:     The surface tension of a liquid results from an imbalance of intermolecular attractive forces, the cohesive forces between molecules:   A molecule in the bulk liquid experiences cohesive forces with other molecules in all directions.   A molecule at the surface of a liquid experiences only net inward cohesive forces   If this is the case: Why is surface tension considered or experienced as a force parallel to the interface while it is so obvious that it must be perpendicular to it? Incorrect icons on hot network questions I see the same problem has occurred in the past, the most-linked one being   Is this happening for anyone else?   I've marked the icons I could recognize as incorrect.  This exists on every page, is on both chrome and firefox (from Ubuntu 16.04), and persists after hard-refreshes in each.  Edit: The icons in Meta's Hot Network Questions tab appear to be consistently accurate. Every other page I checked (including Unix, Workplace, English Language &amp; Usage, Money, and Sci-fi) have a handful of incorrect ones, even for some of the same questions that are displayed correctly in Meta.  Further note: if it matters, the icons are also incorrect in the drop down community-search feature on the right end of the header. Again, they appear correct on this Meta page, and incorrect on all other pages I've checked. Some of the ones that are consistently incorrect:   computational science constructed languages movies and TV raspberri pi rpg russian language science fiction and fantasy sitecore skeptics super user latex workplace   That distribution seems skewed, but I may just be disproportionately familiar with the sites at the end of the alphabet. Many others could be wrong, those are just the ones I could recognize.    Last edit: apparently my Google skills were lacking -  was asked an hour prior. When can an autonomous system be written using a Hamiltonian? Linear algebra skew symmetric When I install "Installer for Microsoft TrueType core fonts" (ttf-mscorefonts-installer) from the Software Center on 14.04, it gives a positive response--but after this I get a download error. It seems that the files actually providing the fonts are never retrieved. Is there any way to resolve this? Function $f: \mathbb{R} \to \mathbb{R}$ that takes each value in $\mathbb{R}$ three times Does there exist a function $f: \mathbb{R} \to \mathbb{R}$ that takes each value in $\mathbb{R}$ three times? If not, how could I prove that such a function does not exist? I have searched in %appdata%, pulling up the list of files there, but there is no file labelled .minecraft. Searching %appdata%\.minecraft returns "no results found".   I also opened Minecraft to click on the resources button and could not locate that either. how do we know the BBP formula for $\pi$ is valid? I recently read about the Bailey–Borwein–Plouffe formula for calculating the $n^{\rm th}$ digit of $\pi$. I'm curious to how can we be sure that the formula is always accurate or correct?! Even if we can verify for every $\pi$ digit discovered till now with a "standard formula", how do we know that the formula is correct after those digits?  Also, what's the implication of these kind of BBP formulas for other "divine"/fundamental constants? can we learn anything else about the value of such constants and our universe through these? Any insight into the "supreme fascist" mind? How to set the default program for opening files without an extension in Windows? How to set the default program for opening files without an extension in Windows?