Some fire chiefs in California say that residents should always be encouraged to evacuate, but Naomi Brown, from the Australasian Fire and Emergency Service Authorities Council, says installing effective early warning systems is the key.

VOA: standard.2009.06.24

Another question is: at what angle should you fire your projectile so it will go the furthest?

另一个问题是以多大角度抛出,物体能飞得最远

耶鲁公开课 - 基础物理课程节选

Another question is: at what angle should you fire your projectile so it will go the furthest?

另一个问题是以多大角度抛出,物体能飞得最远

耶鲁公开课 - 基础物理课程节选