Many words end in the suffixes -ible and -able, and it is often hard to know which spelling to use.
For example, why is it probable but possible?
In fact, words ending in -able are far more common than ones ending in -ible, so if you are not sure then it is best to use -able.
Here is a list of common words that do end in -ible. It is a good idea to learn them. (There are some more, but they are not as common.)
visible (and invisible)
possible (and impossible)
In this worksheet you can practise spelling words ending in -ible and -able.