The thing that pisses me off about English spelling is whether to use a -ent ending or and -ant ending, or whether it's -ery or -ary.

I always get it wrong. And maybe there's a rule so you know which is which but I don't know it.

Like you have the word imagine, so you'd expect imaginary to be spelt with an -ery ending, wouldn't you? But no, it's -ary. Of course!