Hong Kong health authorities closed off the hotel on May 1 after a confirmed swine flu case - a Mexican tourist who stayed there.

VOA: standard.2009.05.08

That may be t=0, t=1, t=2 and so on.

也就是 t=0,t=1,t=2 等等

耶鲁公开课 - 基础物理课程节选

Authorities arrested a Pakistan-born U.S.citizen, Faisal Shahzad, two days after an explosive device inside a sports utility vehicle failed to detonate in Times Square on May 1.

VOA: standard.2010.05.14