I've been strengthening you've been strengthening she's been strengthening we've been strengthening you've been strengthening they've been strengthening
I'll be strengthening you'll be strengthening she'll be strengthening we'll be strengthening you'll be strengthening they'll be strengthening
Future perfect
I'll have strengthened you'll have strengthened she'll have strengthened we'll have strengthened you'll have strengthened they'll have strengthened
Future perfect continuous
I'll have been strengthening you'll have been strengthening she'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 she'd be strengthening we'd be strengthening you'd be strengthening they'd be strengthening
Past
I'd have strengthened you'd have strengthened she'd have strengthened we'd have strengthened you'd have strengthened they'd have strengthened
Past continuous
I'd have been strengthening you'd have been strengthening she'd have been strengthening we'd have been strengthening you'd have been strengthening they'd have been strengthening