He/She probably saw a bird.
If there was nothing in the sky when he/she started barking, and he/she is in the middle of a field with nothing surrounding it, then it could be that he/she has some problems.
If he/she is barking from your backyard then it might be there is a noise coming from the roof. It could a squirrel...
Examples of the sentence using pronouns.It barks at the cat.The dog barks at it.He barks at the cat.The dog barks at her.She barks at him.
barking
"Hello, how are you?" Woof.
croaks
A seal ! (or a dog !)
dog
bark back
I am guessing a seal
get a muzzle maybe? (for the dog obviously) :)
"A dog will bark" is that sentence in the future tense.
A puppy barks at everything. Older dogs know better. They only bark at things that are not normal, such as a burglar or something wrong. This phrase means that when an old dog barks, it means something.
My dog barks when I play the sax