Vigilance tasks provide signals that are infrequent and unpredictable --which is exactly what is expected of the dogs when they are asked to notice just a few odour molecules in the air,and then to home in on the source.
请问最后一个分居里面，in和on怎么连一起了，这个 in感觉有点多余啊
sent from my nexus 4 with android 5.1.1 lollipop system
请问最后一个分居里面，in和on怎么连一起了，这个 in感觉有点多余啊
sent from my nexus 4 with android 5.1.1 lollipop system
