off adv From a place or position
drive off - drive away from a place
The man got into his car and drove off.
那男人上了汽车就开走了。
start off - start from a place
At night I started off upon my journey.
当晚, 我又踏上了征程。
come off - 成功 (informal)
Here the meaning has changed from the main verb "come". It's a new phrase.
He made several attempts but none of them came off.
他进行了几次尝试, 但却没成功。
