I've been extemporising you've been extemporising he's been extemporising we've been extemporising you've been extemporising they've been extemporising
I'll be extemporising you'll be extemporising he'll be extemporising we'll be extemporising you'll be extemporising they'll be extemporising
Future perfect
I'll have extemporised you'll have extemporised he'll have extemporised we'll have extemporised you'll have extemporised they'll have extemporised
Future perfect continuous
I'll have been extemporising you'll have been extemporising he'll have been extemporising we'll have been extemporising you'll have been extemporising they'll have been extemporising
I'd be extemporising you'd be extemporising he'd be extemporising we'd be extemporising you'd be extemporising they'd be extemporising
Past
I'd have extemporised you'd have extemporised he'd have extemporised we'd have extemporised you'd have extemporised they'd have extemporised
Past continuous
I'd have been extemporising you'd have been extemporising he'd have been extemporising we'd have been extemporising you'd have been extemporising they'd have been extemporising