"The cat cannot come along."
Translation:Katten kan ikke bli med.
"Bli med", or by some speakers "være med". They mean slightly different things also. "Bli med" is mostly used for "to join", and "komme med" is more "to be included". For example, you would say "Kan jeg bli med på laget?" - "Can I join the team?", whereas if you say "Komme med på laget" it means to be part of the outtake for the team, for instance before an important match. So a zlightly different tone to it.
It has been answered above.
But - "langs" is only used in a positional sense of the word "along" (and in some figurative ways relating to that understanding). So "along the wall/road" etc. would be translated as "langs veggen/veien" osv.
The understanding of "along" as accompanyment is never translated with "langs" and has to be rephrased. Most commonly with the preposition "med", as in "bli med" for "come along".