if you're free
もし私が暇だったら君を手伝うことができるのに。
If I had free time, I could help you.
彼は暇だったら、魚釣りに行っていただろう。
If he had had time, he would have gone fishing.
もし暇だったら手伝えるのに。
If I were free, I could help you.
暇だったら、手伝ってください。
If you have time, please help me.