I've been strengthening you've been strengthening he's been strengthening we've been strengthening you've been strengthening they've been strengthening
I'll be strengthening you'll be strengthening he'll be strengthening we'll be strengthening you'll be strengthening they'll be strengthening
Futuro perfecto
I'll have strengthened you'll have strengthened he'll have strengthened we'll have strengthened you'll have strengthened they'll have strengthened
Futuro perfecto contínuo
I'll have been strengthening you'll have been strengthening he'll have been strengthening we'll have been strengthening you'll have been strengthening they'll have been strengthening
I'd be strengthening you'd be strengthening he'd be strengthening we'd be strengthening you'd be strengthening they'd be strengthening
Passado
I'd have strengthened you'd have strengthened he'd have strengthened we'd have strengthened you'd have strengthened they'd have strengthened
Passado continuo
I'd have been strengthening you'd have been strengthening he'd have been strengthening we'd have been strengthening you'd have been strengthening they'd have been strengthening