function changePan(){
var latlngbounds = new GLatLngBounds( );
latlngbounds.extend(new GLatLng(39.907,116.387));
latlngbounds.extend(new GLatLng(39.935,116.407));
latlngbounds.extend(new GLatLng(39.944,116.432));
latlngbounds.extend(new GLatLng(39.924,116.427));
map.setCenter( latlngbounds.getCenter( ), map.getBoundsZoomLevel( latlngbounds ) );
}