Talking of grammar....

Sometimes the pragmatic way in which English is taught by Chinese teachers can be so frustrating.

They NEED a 'rule', even when there isn't one!

Today I was asked - 'Is it wise FOR you....or wise OF you...?'

I explained that both are often correct and it doesn't really matter, (especially when you apply the 100-year rule), but that wasn't good enough for her.

Common usage plays a huge factor too, but that also wasn't good enough.

In the end I said -

'It would be wise for you to think about where you want to travel this summer before airline fares increase.'

'It was wise of you to choose Thailand as your destination.'

Therefore giving examples using different tenses. Still not good enough because there was no 'rule'.

In both cases, the 'for' and 'of' are interchangeable. There's also no need for you to explain. I know there is a teeny-weeny, nano-sized difference in meaning, but in reality, does it matter? - and in 100 years, will anyone care?