ABSTRACT
A A number of verbs seem to be entirely regular, but they incorporate a change of spelling in one or more of their forms. For example:
(a) stop takes a double p in both participle forms and in the simple past:
stopping stopped they stopped
(b) So does hop:
hopping hopped she hopped
It is especially important to get (b) right, because you otherwise confuse it with hope, whose same forms are:
hoping hoped we hoped
(c) panic adds a k to all three forms; the hard c of the original would otherwise be softened by the i and e:
panicking panicked you panicked
(d) die is regular in past participle and simple past forms, but changes spelling in the present participle:
dying1
Such verbs are, arguably, minorly inconsistent rather than irregular. Pedantically, that may be so; but they cause writers a lot of trouble, and in my view thus earn their place here.