I had never done anything crazy in my life before I started learning how to skydive five months ago.      I never did anything crazy in my life before I started learning......   Are both the above sentences grammatically correct? I see natives not using past perfects all the time.   I was on  and if you would scroll down a bit, you'd see a sentence:     "She never saw a bear before she moved to Alaska."    It is deemed incorrect.
The rule says if the order of two actions/events is clear then the past perfect is not necessary, i.e. you can use past simple. So if the sentence has before or after then the order is clear and therefore the rule applies.  says the first sentence is incorrect. Is he/she right? If so, how do you explain what appears, to me, to be contradictory?     If the Past Perfect is not referring to an action at a specific time,   Past Perfect is not optional. Compare the examples below. Here Past   Perfect is referring to a lack of experience rather than an action at   a specific time. For this reason, Simple Past cannot be used.      Examples:      She never saw a bear before she moved to Alaska. Not Correct      She had never seen a bear before she moved to Alaska. Correct   They say "a lack of experience rather than an action". Saying that just does not solve the problem I have which is the past simple fits the rule of order of events. Not seeing is a negative event with the verb "to see".  I hope the answer won't be this is how we speak or this is how English works or since when languages are logical!
I've had a promising Skype interview with a great professor from a top-level university in US. Our research interests are closely related and he encouraged me to apply BUT he says that all decisions are finally made by admission committee there.  The question is "Is a professor in such a high-level university able to affect admission committee if he really wants a student?" or "Does admission committee decision-making process become easier if a professor really wants an applicant?"  The main point is the difference between my transcript (which is a real catastrophe!) and my research background which is pretty good so the professor's decision might be different from admission committee. Expected area of the intersection of two circles If we pick randomly two points inside a circle centred at $O$ with radius $R$, and draw two circles centred at the two points with radius equal to the distance between them, what is the expected area of the intersection of the two cirlces that contain the origin $O$. Except when we use right to denote direction, what is the difference between these two terms?  Also, which one is the preferred construction between these two     Am I right?   or     Am I correct? What is the correct way to pluralize an acronym / initialism? For example, if I wanted to write the equivalent of  There are many automated teller machines in this city.  Would it be  There are many ATMs in this city.  or  There are many ATM's in this city. (could get confused with possessive form or contraction).  or just  There are many ATM in this city. (assuming the final s is included in Machines represented by M).  Maybe something else? I'm writing a mildly dystopian scenario where competition is taken to vicious extremes, and I was wondering if there was a word that I could use (specifically a noun that was a synonym of "competition") to describe the sort of vicious, cutthroat ... _________ (the word that I want) that was going on.  I'm specifically looking for a word that doesn't refer to a one-off event (like "contest" or "tug-of-war"), but rather is more about the state of things. Partial Fraction Decomposition? If the edges of the complete graph $K_{17}$ (on 17 vertices with no three collinear) are each colored one of three colours can it be proven to have two or more monochromatic triangles? I have a sight hosted on .ie domain but it is near the NI(Northern Ireland) border and the business has a lot of NI traffic. So when someone searches in NI with certain key words I would like the site to appear in the results, it currently doesn't.   I have seen this post    But was wondering the best way around this. Would it be to create a .co.uk version that redirects to the .ie site? Or would I have to create a separate .co.uk site?  Any help appreciated thanks. ^x^y unix trick for all instances in last command? One of my favorite Unix tricks is ^x^y, which will take the last command and replace the first instance of "x" with "y". However, I'm wondering if a similar trick works to replace all instances of "x" with "y" in the last command? Raised index of partial derivative Selecting an ID with a colon in it with jQuery Add air resistance to projectile motion I am given an initial x and y position and initial velocity and I was asked to graph the trajectory in 1 second intervals.  This is what I have so far:  If $x_0 = 1, v_{0x} = 70, y_0 = 0, v_{0y} = 80, a_x = 0, a_y = -9.8$, and time will be 0,1,2,3... and so on.  Using these equations on every second you can find the plot will be a bell shaped with the highest point being ~ 325 m at about 600 seconds:   $$ x = x0 + (v_{0x})t + 1/2((a_x)t^2) $$ $$ y = y0 + (v_{0y})t + 1/2((a_y)t^2) $$  Usually in physics, we are taught in perfect condition with no air resistance. But what if there was air resistance? How would it affect this problem? How can i add it to my calculations and see what the difference is? I understand the purpose of up/downvoting answers -- some answers are better than others, some answers may be wrong, .etc.  With regard to questions, though, there are other mechanisms to deal with "bad" questions:  comments, close, flag.  A poorly written question should be improved.  A bad question should be closed/deleted.  Often, though I see poorly written questions downvoted. I'm not sure what this accomplishes.  I get loss of rep for offensive or spam questions, but for an off-topic question?  or one that is just poorly written?   Why?  It seems to me that rep ought to be based more on answers on a site of this type.   Fundamentally, it seems that rep ought to be based on what you add to the site, not what you ask of it.  A particularly good question does add to the site, but a poor question doesn't really detract from it in the same way that a bad (wrong) answer does. Sure, go ahead and give people more rep for asking a particularly good question, but why punish people for asking bad questions when there are other ways of handling that.  Why not handle questions more like comments and allow upvotes, but not downvotes?  It seems to me that many, if not most, of the downvoted questions are first timers.  It's more likely that your first introduction to the site will be in asking a question, rather than answering. There is a significant risk to alienating new users when their questions are downvoted -- there's a visceral response to seeing that negative number next to your question.  Why not let the close/flag system weed out questions that don't belong and the comment system work to improve poorly worded questions. How to find effects of magical items? Similar to this , but specific to D&amp;D 5e, how are players meant to find out the effects of items/potions/scrolls/weapons/armor?  Say, they find a potion in some chemist's chest. It is red and smells nice. Should they perform an investigation/perception check? Or an arcana/nature check? If I tell the players specifically to do an Arcana check, then I am already hinting at the fact that this potion will have some magical effect. It could just be a natural elixir concocted by Druids to help your health regen.  Same goes for weapons. They find the legendary bow of X, which has a +3 to hit and a 10% chance of striking other enemies near the target. I describe the bow as unique, glowing, made from dragon scales and hovering on air. Would they investigate their properties? Or just I just let them fire at a wall until something happens?   Our playstyle so far has been to use active checks for a quick understanding of the item (drink a little bit of Potion as an Investigation check to find whether it heals or not, sensing magical properties of the bow with Arcana checks). When time is available, and experimentation is necessary, allow the PCs to do some creative testing and, based on their ideas, "After Y time, you realize that the bow sometimes hits several points of the wall instead of just your target".  According to the RAW, is there a specific way of checking the stats/effects of such items? "Belongs on" comments If particles are points, then aren't atoms empty space? Zero dimensional points do not take up space, so then wouldn't everything in the universe be literally empty? Or is there something that I'm missing? I'm new to TDD and xUnit so I want to test my method that looks something like:   List&lt;T&gt; DeleteElements&lt;T&gt;(this List&lt;T&gt; a, List&lt;T&gt; b);   Is there any Assert method that I can use ? I think something like this would be nice  List&lt;int&gt; values = new List&lt;int&gt;() { 1, 2, 3 }; List&lt;int&gt; expected = new List&lt;int&gt;() { 1 }; List&lt;int&gt; actual = values.DeleteElements(new List&lt;int&gt;() { 2, 3 });  Assert.Exact(expected, actual);   Is there something like this ? Simple question but I am confused.  What is the boundary of $S^2\times\mathbb{R}$? Is it just $S^2$?  What would be the general way to evaluate the boundary of a product manifold?  Thanks for the replies! Google search results showing up a URL on its search which doesn't exist on the website I am using a keyword to display a website page on google search. After entering the keyword, on the first page of google, I am redirected to a page, whose domain is exactly similar to the website whose page I want to display, but it is showing a page which doesn't even exist on the domain. Also, as similar domain with spam characteristics is also getting displayed.   To practically demonstrate this issue, do follow the below steps.   Go to  Type dolce streichquartett and click on search. The 4th/5th URL has this link http://www.dolce-streichquartett.de/?high_ry=/casinos/de/spielautomaten-casino-bregenz.php, which is no where on the website and looks like spam The 7th/8th link you see is http://deonlinecasino.org/doc/kostenlos-roulette-spielen-spielgeld-ausdrucken.php, which is exactly similar to the above with the title as the keyword but a different domain.   What is this issue and why is this happening? Intuitive explanation of the tower property of conditional expectation I understand how to define conditional expectation and how to prove that it exists.  Further, I think I understand what conditional expectation means intuitively. I can also prove the tower property, that is if $X$ and $Y$ are random variables (or $Y$ a $\sigma$-field) then we have that  $$\mathbb E[X] = \mathbb{E}[\mathbb E [X | Y]].$$  My question is: What is the intuitive meaning of this? It seems quite puzzling to me.  (I could find similar questions but not this one.)