Al-Qaida has already said it's focused on public transport, according to this video featuring an al-Qaida spokesman, the American Adam Gadahn.

VOA: standard.2010.04.01

They're already paying for public transport, so it's just kind of a financial expense they could do without.

他们已经向公共交通付钱了，所以，那只是一笔没有必要的财务支出。

公共交通更方便 - SpeakingMax英语口语达人

regular people got to stick to public transport.

普通人还是坚持用公共交通。

公共交通更方便 - SpeakingMax英语口语达人

Their bombs did not explode. Analyst Jonathan Wood with the security firm Control Risks in London, says public transport systems are an attractive target.

VOA: standard.2010.04.01

But analysts say public transport is hard to police.

VOA: standard.2010.04.01