MontyVeda
a short-tempered ill-controlled small-minded troll
- Location
- Lancaster... the little city.
sorry... 

Because advice/advise both have a long 'i' so it's easy to pronounce them differently; as most people do, with a zed sound for the verb.For some reason I find it very easy to use advice/advise correctly, yet practice/practise seems much harder to get right. Dunno why, despite the common ce/se endings.
I think you were correct. Their, his, my, all refer to a thing, owned by a person. That may be a physical thing (dog, hat), or a concept (skill, soul), but it's a thing, and therefore a noun. You cannot own a verb.
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My usual test of practice/practise, licence/license etc is to use the more obvious advice/advise comparison. Because practice/practise SOUND the same, the spelling isn't obvious. However, substitute the differently sounding advice or advise and the answer leaps out....
''Myriad' nd 'myriad of' are both correct. One of my pet hates is people trying to impress others with their knowledge and ending flat on their faces. Please explain to me what are 'pound British Sterlings'? if you want to use sterling (note - not capitalised) use pound sterling.One of my pet hates turned up in the first para of an article in y'day's Grauniad: a professional journalist, paid in many proud British Sterlings, used the expression 'a myriad of'. Grrrr. Also, harumph.
I met a panda that eats shites and leaves.