1.
You tell someone to ~ to encourage them in a friendly way to do something, especially to attend something.
There’s a big press launch today and you’re most welcome to ~.
= come on
PHRASAL VERB: V P
2.
You say ‘~’ to someone to encourage them to hurry up, usually when you are rather annoyed with them.
Come along, Osmond. No sense in your standing around.
= come on
CONVENTION
3.
When something or someone comes along, they occur or arrive by chance.
I waited a long time until a script came along that I thought was genuinely funny...
It was lucky you came along.
PHRASAL VERB: V P, V P
4.
If something is coming along, it is developing or making progress.
Pentagon spokesman Williams says those talks are coming along quite well...
How’s Ferguson coming along?
PHRASAL VERB: V P adv, V P