come along or come
I cannot understand most frequently meaning expression "come along".
1) "They said it's good if I come along."
2) "You can come along if you want."
My translator translates it like "come along with smb" but for me I could translate these sentances both ways like just "come" or like "come along with smb".
and there are a lof of examples when used come along in meaning just come, and I cannot understand could I use in these cases just come withount alon and what difference between come and come along in these cases...
1) "anybody could come along and build new technology"
2) "Particularly when some engineer has come along with the answer."
3) "A new technology will come along to fix the messes we made with the last one."
for me, in all these cases, I could use just come.
My questions are:
1) What difference between come and come along?
2) Could I use come instead come along almost cases "come along with"?