Welcome back to Learn Academic English! in today's video I'm going to give you an overview
of prefixes in English and to get started we're going to look at a few example
situations the first one is at a work meeting and someone says he miscalculated the costs
the next one is at a dentist so imagine that you're traveling and you have a
dental emergency and you need to see a dentist but the dentist speaks only English and this dentist
says to you we need to extract a tooth at a hospital you might hear a postoperative infection
at school your professor might say to you your argument is invalid or when you read the newspaper
you might see a misappropriation of funds well in all these situations we have these words
that are quite advanced but if you look closely you'll see that each of these words has a prefix
and if you know the prefix it can help you to guess the meaning of these new words so in today's
video I'm going to talk about what prefixes are why they are so helpful to learn and then I will
give you a quick overview of just a few common prefixes in future videos I'll talk about more
prefixes and I will talk about prefixes in more detail and finally at the end of the video I will
show you how knowledge of prefixes can help you on tests like the TOEFL and iELTS tests before
we get started I'd like to ask you to please give this video a like and subscribe if you want more
videos about English for intermediate and advanced English learners from an experienced and trained
English teacher and don't forget to leave a comment below I love to read your comments so
let me know if you can think of other examples of words that have the prefixes that we look at today
so let's get started the first prefix we have is the prefix mis which means incorrect or wrong
and an easy way to remember this one is the word mistake we also have example words like
miscalculate which is the word that I showed you in the previous example to miscalculate
is to calculate the numbers incorrectly we also have verbs like misread misspell and
the noun miscommunication miscommunication means that people misunderstand each other during
communication and I'm sure that you can think of other examples because this is a very common
prefix the next one is post which means after and this one is not as common but we do use it for
example post postoperative postoperative means after an operation after surgery
for example the post-operative instructions or a postoperative infection pos-Covid is a common word
right now and of course you know the verb postpone which means to do something later or after
and if you learn post you should also learn pre because these are a pair they are opposites so
we have post which means after and pre which means before like pre-pay pre-heat this is a very common
verb that we use when we turn the oven on so that it reaches the temperature before we put the food
in the oven we also have prepare and previous so I want to point something out here which is that
some prefixes like preheat pre we can take the prefix off and we are left with a word so for
example preheat take off pre and we have the verb to heat but for prepare or for example postpone
we cannot take the prefix off so just notice that some words the prefix can be taken off or put on
and in other words the prefix has become part of the word so in pre-pair you cannot take off pre
and have the verb pair pre-pair is part of the word the next suffix is ex or e which means out
and an easy way to remember this one is the word exit we have extract that is the example from the
dentist so extract you can imagine if ex means out extract means to take out or to pull out a tooth
we also have export explode where everything comes out and emissions emissions is a common word now
emissions is the pollution that comes out of your car or out of a factory and we often use the word
zero emissions now to refer to cars that produce no pollution no emissions however the prefix ex
has another meaning which is former and you'll notice that with this one we usually use
a hyphen between the parts and former or previous like ex-husband ex-wife ex-girlfriend ex-boyfriend
ex-boss and ex-convict an ex-convict is a person who is a former convict a convict as
a person who was in prison so an ex-convict is a person who used to be in prison but now is free
and the last one I'm going to show you today is this great prefix in for meaning
not and I think it's great because it is kind of interesting because it has different spellings
so this is the prefix that we saw in the previous example of an invalid argument your argument is
invalid invalid means not valid or that it doesn't work it's not true so for this prefix notice that
the spelling can change and i'll show you the rule we have inappropriate immature irregular
and illogical if the word starts with an m you're going to add the prefix im and this
is also the case if the word starts with other sounds that we use both lips to make so m or p
or b impossible imbalanced immature the word starts with an r you add the prefix ir irregular
and if the word starts with an l like logical legal legible you add the prefix il illogical
finally let's take a look at how knowledge of prefixes can help you on the toefl or ielts test
so on those tests you're going to have a lot of reading and there will be a lot of new vocabulary
so knowing prefixes can help you to guess the meaning of a lot of those new words
and there are questions like this one where you are given a new word and you have to match it
with the correct meaning in this example we have in many underdeveloped countries
the number of illiterate people is decreasing so if you look at this word you should recognize that
il is the prefix and you should notice then that il is a prefix that means not so not literate so
the first thing that we'll notice here with the answers is that two of them are answers that
show some kind of negative meaning c and d are not like that so we're going to go ahead and rule
those out and we'll focus just on a and b then if you know literate you might think literature
and letter that that's probably about writing so that would lead us to choose be
now this word might not be difficult for you but if you see other words that are new for you use
your knowledge of prefixes to help you break that word down and then match it with the best answer
finally I want to mention that when you are learning prefixes you want to be careful to
learn words that are really like easy clear examples of the meaning for example
sometimes in my class when I teach prefixes my students give examples of words that don't
match the prefix meaning and I even see these on the internet too so you do have to be careful for
example with the prefix post which means after post office is not an example of that prefix
dis which means not distance is not an example of that prefix what about mr miss means incorrect
but the word mr is not an example of that prefix it's just a word that starts with m-i-s
so when you're learning prefixes do be careful to choose really clear
good examples that help you to remember those words and the meaning of those prefixes
don't forget to leave a comment below and let me know what other examples of these prefixes you can
think of and if you look in the description box you'll notice a link to a handout about prefixes
that you can use to help you study at home until next time take care and I hope to see you soon!