As putin spoke , and as the national audience watched , many in the crowd started to jeer and whistle .
普京正讲着话，全国观众正在电视机前看着直播，现场许多人突然吹起了口哨、喝起了倒彩。
Before the air brake , railroad engineers would stop trains by cutting power , braking their locomotives and using the whistle to signal their brakemen .
