can not -> can't
do not -> don't
did not -> didn't
I am -> I'm
we are -> we're
they are -> they're
I have -> I've
we have -> we've
they have -> they've
is not -> isn't
was not -> wasn't
were not -> weren't
would not -> wouldn't
will not -> won't
could not -> couldn't
should not -> shouldn't
may not -> mayn't
must not -> mustn't
let us -> let's
These are just a few examples, and there are many other words that can be combined to form contractions. Contractions are commonly used in informal writing and speech, and they can help to make sentences flow more smoothly.