present
I strengthen
You strengthen
He strengthens
She strengthens
It strengthens
We strengthen
They strengthen
past
I strengthened
You strengthened
He strengthened
She strengthened
It strengthened
We strengthened
They strengthened
future
I will strengthen
You will strengthen
He will strengthen
She will strengthen
It will strengthen
We will strengthen
They will strengthen
conditional
I would strengthen
You would strengthen
He would strengthen
She would strengthen
It would strengthen
We would strengthen
They would strengthen