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hello grammarians we are once again learning how to master time and become time wizards which is of course what you will be if you master all the tenses of English but if you want to become an additional time wizard if you want to get I don't know second hat that ro knows all wizards where multiple simultaneous hats if you want to wear a second hat on top of your other time wizard hat there's the silliest thing I've ever said then you will have to learn the prepositions of time now here's something weird and cool about prepositions of time is that once upon a time all of these were physical prepositions like before and after just used to mean behind and in front of you know that they later took on this additional connotation of time just over the course of english-speaking history people took this literal meaning of you know before and after and made it representational you know this moment occurred in front of this one in time but behind this other one in time it's a metaphor we're using space to represent time anyway I just thought that was really cool let's talk about how all of these work I'm just gonna list a couple of the most most famous prepositions of time and write an example sentence so let's go through these after and before as we've established these these are time relationships that you know refer to something happening after so when something is completed say the bats come out after the Sun Goes Down and before this occurs prior to some point in time so it is behind in action so you can say can you take out the garbage before you leave the house at is very precise when we're talking about at we're talking about a single moment in time we could say the vampire wakes at 10 p.m. there is emerging from his coffin there is the his oh that's not the Sun the Sun would burn a vampire no that's a um it's his a little clock it's got a tail cuz it's like a little wacky cat clock no a bat clock and that's never that doesn't have a tail it's got a little stubby tail oh I really want a bat clock now anyway okay bye this this is a really precise end time but not a very precise beginning time so you could say something like this place had better be cleaned by 3:00 p.m. buddy and if you say something like that you're not especially concerned that the place might be clean before 3:00 that would be nice but it's only relevant to you that the cutoff time is at 3:00 o'clock so the end is precise that's the connotation there but the beginning is not for denotes duration how long something has been going on so you could say I've been a chef for 40 years I haven't but that would be cool and difficult but you know what this is Khan Academy you can cook anything in denotes a bounded duration so it's something that lasts for a specific amount of time like a limited period okay so let's just say bounded duration so that covers usage like you know in March or in the Middle Ages both of both of those things are like set periods March has a beginning and an end the middle ages have a beginning and an end it's a bounded duration on has a specific connotation it's something that happens on a specific day you could say something like on the fourth of July many Americans watch fireworks and eat encased meats mind you not everybody eats hot dogs or likes fireworks oh I said many not all since is kind of like bi except it's more about the precision of the start point rather than the end point so precise beginning since 1974 our company has made nothing but toasters until is also precise but its precise ending time you have until midnight to rescue the ambassador break the curse and save prince Wilbur right so there's a precise ending there you have until midnight and then you can't rescue the the Ambassador or break the curse or save any princes but what you can do is learn anything these are some of the most essential time prepositions David out