diff --git a/chan/future/main.go b/chan/future/main.go
index 9be5029..01d3f88 100644
--- a/chan/future/main.go
+++ b/chan/future/main.go
@@ -13,8 +13,11 @@ func withFuture(ca, cb string) {
 }
 
 func main(){
+
+	// this is ok, but not ideal, because fa and fb will be invoke sequencely
 	withFuture(<-fa(), <-fb())
 
+	// this is good because fa and fb are invoke concurrently
 	ca, cb := fa(), fb()
 	withFuture(<-ca, <-cb)
 }