--- How come you know the accident so well?--- Well, because I was on the __________.

In order to reduce   air pollution, many people want  a total _____on the playing of firecrackers (鞭炮)in many cities during the Spring Festival.

While the soldier’s idea was interesting, the system was too difficult to be ____.

Security was such a major concern at the conference that no journalists could approach the meeting zone without ________ the special pass.

theirs