Use of word 'alone'

Hi all, I am new to this forum. I am preparing for an competitive exam. There few questions wherein we have to identify the grammatically incorrect sentences fro m a group of sentences. I have a doubt in the following sentence -

-- City A and City B alone account for over 40% of the passenger traffic.

Is the above sentence correct ? or should the word alone be used only for one noun, as in "City A alone accounts for over 40% of the passenger traffic?".

Thanks in advance :-):-)

Welcome to the forum.

You are right. "City A alone ...", "City B alone ..." or "City A and City B together ..."

Please remember that we are happy to help with practice sentences or work which will not be used towards or in an exam situation, but we can't help with homework or with actual test papers.