If somebody reminds you of another person...
If you analyse a problem...
If you doubt something that you've heard...
If you contemplate your future...
If you suspect something is true...
If an idea occurs to you...
If you recollect an experience...
If you memorize a number...
If you consider someone to be attractive...
If you can't comprehend something...
that is your opinion
it comes to your mind suddenly.
you think it probably isn't true
you think about it in a logical way.
they make you think of that another person.
you learn it so that you won't forget it.
you think about it for quite a long time
you think about it at a later date
you don't understand it.
you think it might be true but you aren't sure